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Tools

Open source runs the eval stack, but only its lower layers have settled

Two open harnesses carry most model benchmarking, Docker and OpenTelemetry won the plumbing, and larger companies bought most eval platforms in 2026.

monthly Inspect AI downloads
2.9M
benchmark adapters in Harbor
86
eval-tool deals in 2026
7
Dynatrace price for Arize
$915M
open licences changed after a deal
0
On this page
  1. Key findings
  2. The stack
  3. Harnesses
  4. App and agent evals
  5. Environments and RL
  6. Red team
  7. Traces and formats
  8. Sandboxes, judges, statistics
  9. Owners and licences
  10. Standard vs open
  11. Sources

Key findings

  • Two harnesses carry most model benchmarking. UK AISI's Inspect AI draws 2.9 million PyPI downloads a month, and EleutherAI's lm-evaluation-harness 1.0 million (5 Nov 2026).[3][3] inspect-ai downloads pypistats Primary[7][7] lm-eval downloads pypistats Primary
  • Harbor became the shared unit for agent benchmarks. Its 86 adapters cover SWE-bench, OSWorld, GAIA and HLE, and four other frameworks import its tasks.[33][33] Adapters folder Harbor Primary
  • Academic harnesses age fast. Six well-known projects froze or retired since mid-2024, including HELM (maintenance mode since 1 June 2026) and the Open LLM Leaderboard (retired 13 March 2025).[39][39] HELM README Stanford CRFM Primary[44][44] End of the Open LLM Leaderboard Hugging Face Primary
  • The app eval library is now a commodity. Every platform ships judges, datasets and a CI exit code. Only MLflow 3.18.0 (November 2026) ships a paired test between two runs.[86][86] Comparing evaluation runs MLflow Primary
  • Eval and RL environments merged into one layer. OpenEnv (v0.12.0, 5 Nov 2026), verifiers and Harbor tasks now serve evaluation and training alike.[94][94] OpenEnv GitHub API Primary[109][109] verifiers Harbor docs Prime Intellect Primary
  • OpenTelemetry won the transport, not the vocabulary. The OTel GenAI conventions still carry "Development" status, while OpenInference draws 8.6 million monthly downloads.[142][142] GenAI conventions overview OpenTelemetry Primary[138][138] OpenInference conventions downloads pypistats Primary
  • Larger companies bought most eval platforms in 2026. ClickHouse bought Langfuse (16 Jan), OpenAI bought promptfoo (9 Mar) and Dynatrace closed Arize for $915M (1 Oct).[168][168] Langfuse acquisition ClickHouse Vendor[73][73] Joining OpenAI promptfoo Vendor[174][174] Dynatrace and Arize ITPro Secondary
  • No acquirer changed an open licence. Most core projects stay MIT, Apache-2.0 or BSD. Phoenix's Elastic License and closed ee/ folders are the main traps for a hosted product.[88][88] LICENSE Arize Phoenix Primary[166][166] LICENSE Langfuse Primary
  • No result format has won. Inspect .eval logs lead in practice, while the neutral Every Eval Ever schema drew 285 PyPI downloads last month.[149][149] Inspect eval logs docs UK AISI Primary[151][151] every-eval-ever downloads pypistats Primary

Only the bottom of the eval stack has settled

Every evaluation passes through the same seven layers, whatever the tool. The sandbox and the harness have settled. Grading, statistics and reporting have not.

Every evaluation follows the same path. A team writes tasks and runs them in a sandbox through a harness. Graders score each answer, statistics add error bars, traces keep the evidence, and reports show the result. Figure 1 shows each layer with its leading names and a status tag.

The Sandbox and the Harness Have Settled. Grading and Reporting Have Not.

The seven layers of an evaluation, bottom to top. A solid slab has one de facto choice; a broken slab has rival tools; the dashed slab is a standard still in draft.

Standardone de facto choiceFragmentedmany rival toolsDrafta standard exists but is not finalIn Graders, tile width shows monthlyPyPI downloads (5 Nov 2026). Otherbroken layers use equal tiles.1 · Tasks and datasetsFragmented· what we testHarbor taskslm-eval YAMLHF Datasets2 · Environments and sandboxesStandard· where the agent actsDocker3 · Harness or runnerStandard· runs each taskInspect AI + lm-evaluation-harness4 · GradersFragmented· who scores each runautoevalsDeepEval5 · StatisticsFragmented· how sure we areIntervalsIRT modelspass^kSequential6 · Traces and storageDraft· the evidence trailOTel GenAI conventions · “Development”7 · ReportingFragmented· who sees the resultLeaderboardsDashboardsLab system cardsInspect tasks · 867kRagas · 1.1Mopenevals · 1.0Magentevals · 428kTruLens · 20kSettled: Docker and twoharnesses work almosteverywhere.Still open: graders, statisticsand reports have no winner.
  • 7 · Reporting: Fragmented. Each source picks its own benchmarks and methods. Leaderboards; Dashboards (Langfuse 23.6M and MLflow 19.9M PyPI downloads a month, incl. SDK installs, 5 Nov 2026); Lab system cards
  • 6 · Traces and storage: Draft. OpenTelemetry won the transport; the GenAI terms are still "Development". OTel GenAI conventions; OpenInference (8.6M downloads a month, 5 Nov 2026)
  • 5 · Statistics: Fragmented. Each tool computes intervals in its own way. Confidence intervals; Item-response models; pass^k; Sequential tests
  • 4 · Graders: Fragmented. Code checks, LLM judges, rubrics, reward models and human experts all compete. Tiles show judge libraries, sized by monthly PyPI downloads. autoevals (4.1M PyPI downloads a month, 5 Nov 2026); DeepEval (2.6M PyPI downloads a month, 5 Nov 2026); Ragas (1.1M PyPI downloads a month, 5 Nov 2026); openevals (1.0M PyPI downloads a month, 5 Nov 2026); agentevals (428k PyPI downloads a month, 5 Nov 2026); TruLens (20k PyPI downloads a month, 5 Nov 2026)
  • 3 · Harness or runner: Standard. The de facto pair for model evals. Inspect AI (2.9M PyPI downloads a month, 5 Nov 2026); lm-evaluation-harness (1.0M PyPI downloads a month, 5 Nov 2026)
  • 2 · Environments and sandboxes: Standard. Docker is the shared contract; cloud back ends swap freely. Docker; E2B · Modal · Daytona
  • 1 · Tasks and datasets: Fragmented. Inspect tasks, lm-evaluation-harness YAML and Harbor folders compete. No task format has won. Harbor task folders (4.8M PyPI downloads a month (Harbor), 5 Nov 2026); lm-eval YAML (1.0M PyPI downloads a month (lm-evaluation-harness), 5 Nov 2026); Inspect tasks (867k PyPI downloads a month (inspect_evals), 5 Nov 2026); Hugging Face Datasets
Data table
LayerStateTool or leaderAdoptionDateLicenceSource
7 · ReportingFragmentedLeaderboards (Epoch AI hub, Artificial Analysis, LMArena)
7 · ReportingFragmentedDashboardsLangfuse 23.6M and MLflow 19.9M PyPI downloads a month, incl. SDK installs5 Nov 2026pypistats
7 · ReportingFragmentedLab system cards (Each lab picks its own benchmarks)
6 · Traces and storageDraftOTel GenAI conventions (Status "Development")OpenTelemetry docs
6 · Traces and storageDraftOpenInference (Leads in practice)8.6M downloads a month5 Nov 2026Apache-2.0pypistats
5 · StatisticsFragmentedConfidence intervals (Inspect)
5 · StatisticsFragmentedItem-response models (Epoch AI)
5 · StatisticsFragmentedpass^k (Success on all k tries)
5 · StatisticsFragmentedSequential tests (Stop early when the answer is clear)
4 · GradersFragmentedautoevals (Braintrust)4.1M PyPI downloads a month5 Nov 2026MITpypistats
4 · GradersFragmentedDeepEval (Confident AI)2.6M PyPI downloads a month5 Nov 2026Apache-2.0pypistats
4 · GradersFragmentedRagas (No commits since 24 Feb 2026)1.1M PyPI downloads a month5 Nov 2026Apache-2.0pypistats
4 · GradersFragmentedopenevals (LangChain)1.0M PyPI downloads a month5 Nov 2026MITpypistats
4 · GradersFragmentedagentevals (LangChain)428k PyPI downloads a month5 Nov 2026MITpypistats
4 · GradersFragmentedTruLens20k PyPI downloads a month5 Nov 2026MITpypistats
3 · Harness or runnerStandardInspect AI (UK AISI)2.9M PyPI downloads a month5 Nov 2026MITpypistats
3 · Harness or runnerStandardlm-evaluation-harness (EleutherAI)1.0M PyPI downloads a month5 Nov 2026MITpypistats
2 · Environments and sandboxesStandardDocker (Every major harness runs tasks in Docker containers)
2 · Environments and sandboxesStandardE2B · Modal · Daytona (Interchangeable cloud back ends)
1 · Tasks and datasetsFragmentedHarbor task folders4.8M PyPI downloads a month (Harbor)5 Nov 2026Apache-2.0pypistats
1 · Tasks and datasetsFragmentedlm-eval YAML1.0M PyPI downloads a month (lm-evaluation-harness)5 Nov 2026MITpypistats
1 · Tasks and datasetsFragmentedInspect tasks867k PyPI downloads a month (inspect_evals)5 Nov 2026MITpypistats
1 · Tasks and datasetsFragmentedHugging Face Datasets (Shared dataset hub; no comparable count, so tiles in this layer are equal)
Figure 1. The sandbox and the harness have settled, while grading, statistics and reporting have not. Download counts are monthly PyPI or npm figures on 5 Nov 2026 and include CI traffic. Source: project repositories and docs, GitHub API, pypistats and npm (5 Nov 2026).[3][3] inspect-ai downloads pypistats Primary[7][7] lm-eval downloads pypistats Primary[47][47] promptfoo downloads npm Primary[49][49] deepeval downloads pypistats Primary[142][142] GenAI conventions overview OpenTelemetry Primary[5][5] inspect-evals downloads pypistats Primary[9][9] harbor downloads pypistats Primary[55][55] autoevals downloads pypistats Primary[138][138] OpenInference conventions downloads pypistats Primary

The lower layers have settled. Docker containers, OpenAI-compatible APIs and the two main harnesses work almost everywhere. Cloud sandbox vendors such as E2B, Modal and Daytona now compete as interchangeable back ends.[155][155] Inspect sandboxing docs UK AISI Primary

The upper layers still change fast. Each tool grades, computes statistics, stores and reports in its own way. A different judge can change a ranking. The OpenTelemetry GenAI conventions still carry "Development" status.[142][142] GenAI conventions overview OpenTelemetry Primary

  • LayerDe facto standardOpen alternativeWatch point
    Model benchmarksInspect AI, lm-evaluation-harnesslighteval, OpenCompass, NeMo EvaluatorHELM in maintenance mode
    Agent benchmark tasksHarbor task formatSWE-bench harness, OSWorldDocker cost at scale
    Environments for eval and RLOpenEnv step API, verifierstau2-bench, AppWorld, BrowserGymHub sizes unverified
    App and agent evalsDeepEval (library), promptfoo (CLI)Giskard, openevals, LangWatch ScenarioRagas idle since February 2026
    Self-hosted platformLangfuse, MLflowOpik, AgentaPhoenix under ELv2
    Red teampromptfoogarak, PyRIT, DeepTeamOpenAI owns promptfoo
    TracingOpenTelemetry with OpenInference attributesOTel GenAI conventionsGenAI conventions still "Development"
    Tool accessMCPnoneLicence move to Apache-2.0
    SandboxesDocker imagesKubernetes, Modal, Daytona, E2BVendor lock-in at scale
    Result formatInspect .eval logsEvery Eval EverVery low uptake
    Table 1. Layer-by-layer summary on 5 Nov 2026.

    How to read the download counts. Stars, licences and release dates come from the GitHub API on 5 Nov 2026. Monthly downloads come from the pypistats and npm APIs on the same day. Counts include CI and mirror traffic, so treat them as rough signals. SWE-bench, for example, shows 22.1 million PyPI downloads a month.[1][1] swebench downloads pypistats Primary

Two harnesses carry model benchmarking, and Harbor carries agent tasks

A model-benchmark harness runs a fixed set of tasks against a model and reports scores. Labs, safety institutes and researchers use them to compare models.

UK AISI's Inspect AI leads for agentic, sandboxed and safety evals. It draws 2.9 million PyPI downloads a month, almost three times the count for lm-evaluation-harness.[3][3] inspect-ai downloads pypistats Primary[7][7] lm-eval downloads pypistats Primary Its README lists over 200 ready-made evaluations.[21][21] Inspect AI README UK AISI Primary Each evaluation combines a dataset, solvers and scorers, and MCP tools plug in directly.[22][22] Inspect docs folder UK AISI Primary

Inspect has become a de facto verification standard. Epoch AI's Benchmarking Hub runs on Inspect and shows each question in the Inspect viewer.[27][27] Benchmarking Hub update Epoch AI Primary Hugging Face marks a score as verified only after an Inspect run in HF Jobs.[28][28] Eval Results Hugging Face Hub docs Primary Groq's openbench runs over 95 benchmarks on it.[25][25] openbench README Groq Primary

EleutherAI's lm-evaluation-harness stays the standard for open weights. It defines each task as a YAML file and supports vLLM, SGLang, llama.cpp and OpenAI-compatible APIs.[30][30] lm-evaluation-harness README EleutherAI Primary It also powered the Hugging Face Open LLM Leaderboard.

Harbor became the shared unit for agent benchmarks. A Harbor task is a small folder with an instruction, a Dockerfile and a test script.[32][32] create-task skill Harbor Primary Its 86 adapters include SWE-bench, OSWorld, GAIA and HLE.[33][33] Adapters folder Harbor Primary Inspect, verifiers, OpenEnv and NeMo Evaluator all import Harbor tasks. Harbor is the official harness for Terminal-Bench 2.0.[31][31] Harbor README Primary

The Most-Starred Harnesses Are Not the Most Used

Each dot is a harness: GitHub stars (across) against monthly PyPI downloads (up, log scale), 5 November 2026.

Monthly PyPI downloads (thousands), log scale0.51251020501002005001,0002,0005,00010,00020,00050,000k02,0004,0006,0008,00010,00012,00014,00016,000GitHub starsHarbor4.8M a monthInspect AI2.9M a month with 3,185starslm-evaluation-harnessMost stars, 1.0M a monthSWE-benchMostly CI trafficlightevalLikely a data gapHELMMaintenance since 1 Jun 2026inspect_evalsOpenCompassopenbench
  • Very active or active
  • Maintenance mode
Data table
PointGitHub starsMonthly PyPI downloads (thousands)CategoryNote
Harbor68214,800kVery active or active4.8M a month
Inspect AI31852,900kVery active or active2.9M a month with 3,185 stars
lm-evaluation-harness144081,000kVery active or activeMost stars, 1.0M a month
inspect_evals733867kVery active or active
SWE-bench614922,100kVery active or activeMostly CI traffic
lighteval25796kVery active or activeLikely a data gap
OpenCompass75633kVery active or active
openbench8312kVery active or active
HELM29641kMaintenance modeMaintenance since 1 Jun 2026
Figure 2. Harbor and Inspect lead current use; lm-evaluation-harness has the most stars among active harnesses but a third of Inspect's downloads. SWE-bench's 22.1M a month comes mostly from CI. lighteval's 6k looks too low for its star count and is likely a data gap. Harnesses without a PyPI count are left out: OpenAI Evals (19,709 stars, dormant), simple-evals (4,695, frozen since July 2025), BIG-bench (3,245, archived), NeMo Evaluator (359) and the HAL harness (308, archived). Source: GitHub API and pypistats API (5 Nov 2026).[1][1] swebench downloads pypistats Primary[2][2] Inspect AI GitHub Primary[3][3] inspect-ai downloads pypistats Primary[5][5] inspect-evals downloads pypistats Primary[6][6] lm-evaluation-harness GitHub Primary[7][7] lm-eval downloads pypistats Primary[8][8] Harbor GitHub API Primary[9][9] harbor downloads pypistats Primary[10][10] SWE-bench GitHub Primary[11][11] OpenCompass GitHub Primary[12][12] lighteval GitHub Primary[13][13] lighteval downloads pypistats Primary[15][15] openbench GitHub Primary[16][16] HELM GitHub Primary

Inspect also ships the strongest statistics of any harness. It offers standard errors, bootstrap errors, Wilson intervals, clustered errors and Krippendorff's alpha for judge agreement.[29][29] Inspect metrics docs UK AISI Primary

Academic leaderboard harnesses age fast. Six well-known projects froze or retired since mid-2024. Stanford's HELM entered maintenance mode on 1 June 2026.[39][39] HELM README Stanford CRFM Primary OpenAI stopped updating simple-evals in July 2025.[41][41] simple-evals README OpenAI Primary Hugging Face retired the Open LLM Leaderboard on 13 March 2025.[44][44] End of the Open LLM Leaderboard Hugging Face Primary

Well-Known Eval Projects Freeze Every Few Months

Projects that froze, retired or went idle, July 2024 to November 2026.

Jul ’24Jan ’25JulJan ’26JulNowHarnesses and leaderboardsHELM entersmaintenance mode Lakera PINTbenchmark archived simple-evals frozen Still hostsHealthBench, Open LLM Leaderboardretired Results stay asdatasets; Eval BIG-bench last push;repo archived App and platform toolsHelicone hostedproduct inmaintenance After Mintlify deal Ragas last commit Treat as unmaintained langsmith-sdkmonorepo archived SDKs moved to two newrepos

What to notice

  • Five of the eight events fall in 2026.
Data table
DateLaneEventKindNote
2024-07Harnesses and leaderboardsBIG-bench last push; repo archivedshutdown
2025-03-13Harnesses and leaderboardsOpen LLM Leaderboard retiredshutdownResults stay as datasets; Eval Results replaces it
2025-07Harnesses and leaderboardssimple-evals frozenshutdownStill hosts HealthBench, BrowseComp, SimpleQA code
2026-02-24App and platform toolsRagas last commitotherTreat as unmaintained
2026-03-03App and platform toolsHelicone hosted product in maintenanceshutdownAfter Mintlify deal
2026-04Harnesses and leaderboardsLakera PINT benchmark archivedshutdown
2026-06-01Harnesses and leaderboardsHELM enters maintenance modeshutdown
2026-10-16App and platform toolslangsmith-sdk monorepo archivedotherSDKs moved to two new repos
Figure 3. Static benchmarks saturate, and nobody funds their upkeep. Teams that build on a harness should check its funding as well as its features. OpenAI Evals (dormant) and the HAL harness (archived) have no clear end date and are not shown. Source: project READMEs and the GitHub API (5 Nov 2026).[19][19] BIG-bench GitHub Primary[39][39] HELM README Stanford CRFM Primary[41][41] simple-evals README OpenAI Primary[44][44] End of the Open LLM Leaderboard Hugging Face Primary[69][69] langsmith-sdk GitHub Primary[76][76] Ragas commits GitHub Primary[132][132] PINT benchmark GitHub Primary[169][169] Helicone acquisition Mintlify Vendor
  • ProjectMaintainerLicenceStarsMonthly downloadsStatusBest for
    Inspect AI[2][2] Inspect AI GitHub PrimaryUK AISI, with Meridian LabsMIT3,1852.9M[3][3] inspect-ai downloads pypistats PrimaryVery activeAgentic, sandboxed and safety evals
    inspect_evals[4][4] inspect_evals GitHub PrimaryGenerality Labs, with UK AISIMIT733867k[5][5] inspect-evals downloads pypistats PrimaryVery activeReady-made evals for Inspect
    lm-evaluation-harness[6][6] lm-evaluation-harness GitHub PrimaryEleutherAIMIT14,4081.0M[7][7] lm-eval downloads pypistats PrimaryVery activeOpen-weights and log-likelihood benchmarks
    Harbor[8][8] Harbor GitHub API PrimaryHarbor Framework team (Terminal-Bench)Apache-2.06,8214.8M[9][9] harbor downloads pypistats PrimaryVery activeContainerised agent benchmarks
    SWE-bench[10][10] SWE-bench GitHub PrimarySWE-bench team (Princeton, Stanford)MIT6,14922.1M (CI-heavy)[1][1] swebench downloads pypistats PrimaryActiveCoding-agent benchmark
    OpenCompass[11][11] OpenCompass GitHub PrimaryShanghai AI LabApache-2.07,5633kActiveChinese and multimodal benchmarks
    lighteval[12][12] lighteval GitHub PrimaryHugging FaceMIT2,5796k (likely a data gap)[13][13] lighteval downloads pypistats PrimaryActive, no release in 2026Hugging Face models and tasks
    NeMo Evaluator[14][14] NeMo Evaluator GitHub PrimaryNVIDIAApache-2.0359n/aActiveBenchmarks with interceptors
    openbench[15][15] openbench GitHub PrimaryGroqMIT8312kActiveProvider benchmarks on Inspect
    HELM[16][16] HELM GitHub PrimaryStanford CRFMApache-2.02,9641kMaintenance since 1 Jun 2026Historical comparisons
    OpenAI Evals[17][17] OpenAI Evals GitHub PrimaryOpenAIMIT19,709n/aDormantOld eval registry
    simple-evals[18][18] simple-evals GitHub PrimaryOpenAIMIT4,695n/aFrozen since Jul 2025Reference code for HealthBench, BrowseComp, SimpleQA
    BIG-bench[19][19] BIG-bench GitHub PrimaryGoogleApache-2.03,245n/aArchivedHistorical tasks
    HAL harness[20][20] HAL harness GitHub PrimaryPrinceton PLInone stated308n/aArchivedHistorical agent leaderboard
    Table 2. GitHub API and pypistats, 5 Nov 2026.

    The Inspect ecosystem. Meridian Labs builds the web UI and add-ons for transcript analysis, workflows at scale, Harbor tasks, monitors and cloud sandboxes.[23][23] Meridian Labs repos GitHub search Primary Generality Labs, a London nonprofit, maintains inspect_evals and now accepts pull requests only from approved contributors.[24][24] inspect_evals README Primary NVIDIA's NeMo Evaluator exports Inspect logs.[26][26] NeMo Evaluator README NVIDIA Primary Solvers can be ReAct agents, custom agents, multi-agent setups or a human. An "agent bridge" lets Inspect run outside agents.[22][22] Inspect docs folder UK AISI Primary

    lm-evaluation-harness details. A plugin system from September 2026 lets teams add backends, filters and metrics from their own packages.[30][30] lm-evaluation-harness README EleutherAI Primary Backends also include Hugging Face, NeMo and Megatron-LM. The Hugging Face backend stays the reference, and a script checks vLLM results against it. The README claims use in hundreds of papers and names NVIDIA, Cohere, BigCode, Nous Research and Mosaic ML.

    Harbor and SWE-bench details. Harbor evaluates any agent, such as Claude Code, OpenHands or Codex CLI, and runs thousands of environments in parallel on cloud sandboxes. It also generates RL rollouts.[31][31] Harbor README Primary Terminal-Bench 1 now sends new users to Harbor.[34][34] Terminal-Bench 1 README Primary SWE-bench runs tasks in Docker and on Modal. It released SWE-bench Multimodal v2, with 480 tasks, on 1 September 2026.[35][35] SWE-bench README Primary

    Other active harnesses. lighteval claims over 1,000 tasks, but its last tagged release dates from November 2025.[36][36] lighteval README Hugging Face Primary OpenCompass added the OpenAI Responses API and a LiteLLM gateway in July 2026. In September 2026 it released AgentCompass, which separates models, benchmarks, harnesses and environments.[37][37] OpenCompass README Primary NeMo Evaluator adds an interceptor proxy, confidence intervals and Harbor agents.[26][26] NeMo Evaluator README NVIDIA Primary Epoch AI fits a Bayesian item-response model in its Capabilities Index package.[38][38] Capabilities Index package Epoch AI Primary

    Frozen and retired, in detail. HELM publishes a policy page on what maintenance mode covers.[40][40] Maintenance mode policy HELM Primary The OpenAI Evals README sends users to the OpenAI Dashboard; recent commits only pin CI dependencies.[42][42] Evals README OpenAI Primary Princeton archived the HAL harness, and the team now works on agent reliability.[43][43] HAL harness README Princeton PLI Primary Open LLM Leaderboard results stay available as datasets.[45][45] Leaderboards docs Hugging Face Primary Its successor, Eval Results, stores scores in each model repo and feeds per-benchmark boards.[28][28] Eval Results Hugging Face Hub docs Primary

The app eval library became a commodity; platforms now compete on traces and simulation

These tools test a team's own application or agent, not a bare model. Code-first libraries run tests in a script or in CI. Platforms add trace storage, dashboards, datasets and human review.

Every tool now ships the same core. All of them offer LLM judges, datasets, experiments and a pass-or-fail exit code for CI.[92][92] CI/CD docs promptfoo Primary[93][93] Experiments in CI/CD Langfuse Primary Most gates compare a pass rate with a fixed threshold. Few tools say with statistical confidence whether a change made the agent worse.

Only MLflow ships a paired test. Version 3.18.0, from early November 2026, compares two runs with McNemar or Wilcoxon tests and a bootstrap interval.[86][86] Comparing evaluation runs MLflow Primary No other platform ships a paired test today.

Download counts favour platforms with production SDKs. Langfuse draws 23.6 million PyPI downloads a month, and MLflow 19.9 million.[59][59] langfuse downloads pypistats Primary[61][61] mlflow downloads pypistats Primary Both counts include SDK installs in production apps, so they overstate pure eval use. Among code-first libraries, autoevals and DeepEval lead.[55][55] autoevals downloads pypistats Primary[49][49] deepeval downloads pypistats Primary

Two Platforms With Production SDKs Dwarf the Eval Libraries

Monthly PyPI downloads, in millions, on 5 November 2026. promptfoo is an npm package and is shown with its npm count.

0M5M10M15M20M25M30MMonthly PyPI downloads (millions)LangfuseClickHouse · MIT + closed ee/23.6Mincl. SDKMLflowDatabricks-led · Apache-2.019.9Mincl. SDKautoevalsBraintrust · MIT4.1Mpromptfoo (npm)OpenAI · MIT3.6MDeepEvalConfident AI · Apache-2.02.6MOpikComet · Apache-2.01.7MRagasVibrantLabs · Apache-2.01.1Midle since 24 Feb 2026↳ Still 1.1M a month with no commits since FebruaryopenevalsLangChain · MIT1.0MEvidentlyEvidently AI · Apache-2.0823kW&B WeaveCoreWeave · Apache-2.0 SDK817kArize PhoenixDynatrace · Elastic-2.0626kagentevalsLangChain · MIT428kLangWatch ScenarioLangWatch · Apache-2.0128kTruLensTruEra · MIT20kGiskard v3Giskard · Apache-2.013kAgentaAgenta · MIT + closed ee/13k
  • Trace-and-eval platform
  • Code-first library
  • npm package
Data table
ItemValueCategory
Langfuse (ClickHouse · MIT + closed ee/)23.6MTrace-and-eval platform
MLflow (Databricks-led · Apache-2.0)19.9MTrace-and-eval platform
autoevals (Braintrust · MIT)4.1MCode-first library
promptfoo (npm) (OpenAI · MIT)3.6Mnpm package
DeepEval (Confident AI · Apache-2.0)2.6MCode-first library
Opik (Comet · Apache-2.0)1.7MTrace-and-eval platform
Ragas (VibrantLabs · Apache-2.0)1.1MCode-first library
openevals (LangChain · MIT)1.0MCode-first library
Evidently (Evidently AI · Apache-2.0)823kTrace-and-eval platform
W&B Weave (CoreWeave · Apache-2.0 SDK)817kTrace-and-eval platform
Arize Phoenix (Dynatrace · Elastic-2.0)626kTrace-and-eval platform
agentevals (LangChain · MIT)428kCode-first library
LangWatch Scenario (LangWatch · Apache-2.0)128kCode-first library
TruLens (TruEra · MIT)20kCode-first library
Giskard v3 (Giskard · Apache-2.0)13kCode-first library
Agenta (Agenta · MIT + closed ee/)13kTrace-and-eval platform
Figure 4. Langfuse and MLflow counts include SDK installs in production apps, so they overstate pure eval use. promptfoo draws 3.6M npm downloads a month; Langfuse adds 7.7M npm and autoevals 2.3M npm. Ragas is faded because its last commit dates from 24 Feb 2026. Source: pypistats and npm APIs (5 Nov 2026).[47][47] promptfoo downloads npm Primary[49][49] deepeval downloads pypistats Primary[55][55] autoevals downloads pypistats Primary[59][59] langfuse downloads pypistats Primary[61][61] mlflow downloads pypistats Primary[63][63] opik downloads pypistats Primary

Platforms now compete on three things. They compete on trace storage at scale, on simulated users and on scoring agent trajectories. DeepEval ships a conversation simulator, and LangWatch Scenario tests agents against a simulated user and a judge.[83][83] Scenario README LangWatch Primary LangChain's agentevals scores trajectories with strict, unordered, subset and superset match modes.[79][79] agentevals README LangChain Primary

Every Tool Gates CI, but Only MLflow Runs a Paired Test

Features that the leading app and agent eval tools document, November 2026. Full = documented; Partial = limited; None = not offered; n/a = not stated in our sources.

ToolCI pass/fail gate OpenTelemetry traces ingest or exportSimulated users Trajectory checks Paired test vs baseline
promptfoo OpenAI · MIT Documented GitHub Action before/after Documented OTLP receiver Not stated in our sources Documented checks against traces Not offered
CI pass/fail gate: GitHub Action before/afterOpenTelemetry traces: OTLP receiverTrajectory checks: checks against traces
DeepEval Confident AI · Apache-2.0 Documented deepeval test run Documented exporter Documented conversation simulator Limited tool correctness, plan adherence Not offered
CI pass/fail gate: deepeval test runOpenTelemetry traces: exporterSimulated users: conversation simulatorTrajectory checks: tool correctness, plan adherence
Langfuse ClickHouse · MIT + ee/ Documented Documented OTel endpoint Not stated in our sources Not stated in our sources Not offered
OpenTelemetry traces: OTel endpoint
MLflow Databricks-led · Apache-2.0 Documented Documented Not stated in our sources Not stated in our sources Documented McNemar / Wilcoxon + bootstrap
Paired test vs baseline: McNemar / Wilcoxon + bootstrap
Arize Phoenix Dynatrace · ELv2 Documented Documented OpenInference Not stated in our sources Not stated in our sources Not offered
OpenTelemetry traces: OpenInference
TruLens TruEra · MIT Documented Documented Not stated in our sources Not stated in our sources Not offered
LangWatch Scenario LangWatch · Apache-2.0 Documented Not stated in our sources Documented simulated user + judge Not stated in our sources Not offered
Simulated users: simulated user + judge
agentevals LangChain · MIT Documented Not stated in our sources Not stated in our sources Documented 4 match modes Not offered
Trajectory checks: 4 match modes

What to notice

  • Read the shaded column: only MLflow has a full mark.
Figure 5. Every tool gates CI, and most now speak OpenTelemetry. Simulated users and trajectory checks are spreading. Only MLflow runs a paired test between a candidate and a baseline. Source: project docs and READMEs (5 Nov 2026).[71][71] Tracing docs promptfoo Primary[72][72] GitHub Action docs promptfoo Primary[75][75] CI/CD docs DeepEval Primary[79][79] agentevals README LangChain Primary[82][82] TruLens README Primary[83][83] Scenario README LangWatch Primary[85][85] llms.txt Langfuse Primary[86][86] Comparing evaluation runs MLflow Primary[88][88] LICENSE Arize Phoenix Primary[92][92] CI/CD docs promptfoo Primary[93][93] Experiments in CI/CD Langfuse Primary

Three gaps stay common. Few tools test a pure black-box agent without code. Few ship stateful copies of business tools. Only MLflow runs a paired test between a candidate and a baseline.

Some popular libraries have slowed. Ragas made RAG metrics such as faithfulness popular, but its last commit dates from 24 February 2026.[76][76] Ragas commits GitHub Primary Giskard rewrote its library as v3 for multi-turn agents and no longer maintains v2.[77][77] OSS README Giskard Primary LangChain archived its langsmith-sdk monorepo on 16 October 2026; the platform stays closed.[69][69] langsmith-sdk GitHub Primary

  • ProjectMaintainerLicenceStarsMonthly downloadsStatusBest for
    promptfoo[46][46] promptfoo GitHub PrimaryOpenAI (acquired 2026, deal closed)MIT26,875npm 3.6M[47][47] promptfoo downloads npm PrimaryVery activeYAML evals, CI gates, red team
    DeepEval[48][48] DeepEval GitHub PrimaryConfident AIApache-2.019,3182.6M[49][49] deepeval downloads pypistats PrimaryVery activePytest-style tests in Python
    Ragas[50][50] Ragas GitHub PrimaryVibrantLabsApache-2.016,2471.1MIdle since 24 Feb 2026RAG metrics
    Giskard v3[51][51] Giskard GitHub PrimaryGiskard (Paris)Apache-2.05,94513kActive, new rewriteMulti-turn agent checks and scans
    openevals[52][52] openevals GitHub PrimaryLangChainMIT1,2441.0MActiveReady-made LLM judges
    agentevals[53][53] agentevals GitHub PrimaryLangChainMIT757428kSlowingTrajectory scoring
    autoevals[54][54] autoevals GitHub PrimaryBraintrustMIT1,0724.1M, npm 2.3M[55][55] autoevals downloads pypistats PrimaryActiveScorer library in Python and TS
    TruLens[56][56] TruLens GitHub PrimaryTruEra, with Snowflake tiesMIT3,62820kActiveFeedback functions, RAG triad
    LangWatch Scenario[57][57] LangWatch Scenario GitHub PrimaryLangWatch (Amsterdam)Apache-2.01,015128kActiveSimulated users against agents
    Langfuse[58][58] Langfuse GitHub PrimaryClickHouse (acquired Jan 2026)MIT, plus closed ee/37,05823.6M, npm 7.7M[59][59] langfuse downloads pypistats PrimaryVery activeSelf-hosted traces and evals
    MLflow[60][60] MLflow GitHub PrimaryDatabricks-led open projectApache-2.028,69319.9M[61][61] mlflow downloads pypistats PrimaryVery activeEvals inside an ML platform
    Opik[62][62] Opik GitHub PrimaryCometApache-2.023,2001.7M[63][63] opik downloads pypistats PrimaryVery activeSelf-hosted platform, fully open
    Arize Phoenix[64][64] Arize Phoenix GitHub PrimaryDynatrace (acquired Oct 2026)Elastic-2.012,161626kVery activeTracing and evals, not for resale as a service
    W&B Weave[65][65] W&B Weave GitHub PrimaryCoreWeaveApache-2.0 (SDK only)1,145817kActiveTeams already on W&B
    Evidently[66][66] Evidently GitHub PrimaryEvidently AIApache-2.08,042823kSlowingML and LLM monitoring reports
    Agenta[67][67] Agenta GitHub PrimaryAgenta (Berlin)MIT, plus closed ee/4,88713kVery activePrompt playground and evals
    Kiln[68][68] Kiln GitHub PrimaryKilnMIT library, source-available app5,255n/aActiveDesktop eval and fine-tune app
    LangSmith SDK[69][69] langsmith-sdk GitHub PrimaryLangChainMIT (platform closed)1,083 (old repo)n/aOld repo archived 16 Oct 2026Teams on LangSmith
    Table 3. GitHub API, pypistats and npm, 5 Nov 2026.

    Code-first libraries.

    • promptfoo puts evals in YAML files with providers, prompts, tests and assertions. It calls any HTTP, WebSocket or MCP endpoint.[70][70] HTTP provider docs promptfoo Primary It receives OpenTelemetry traces and checks agent trajectories against them.[71][71] Tracing docs promptfoo Primary A GitHub Action runs a before-and-after comparison on each pull request.[72][72] GitHub Action docs promptfoo Primary The company claims 350,000 developers and teams at over a quarter of the Fortune 500 (vendor claim).[73][73] Joining OpenAI promptfoo Vendor Release 0.125.1 shipped on 25 October 2026.
    • DeepEval writes tests as pytest-style LLMTestCase objects. Its metrics include G-Eval, task completion, tool correctness and plan adherence. deepeval test run gates CI.[75][75] CI/CD docs DeepEval Primary
    • Giskard v3 splits into giskard-checks, giskard-scan and giskard-agents.[77][77] OSS README Giskard Primary
    • openevals builds judges with one create_llm_as_judge call.[78][78] openevals README LangChain Primary autoevals offers LLM, heuristic, embedding and RAG scorers in Python and TypeScript.[80][80] autoevals repo Braintrust Primary Braintrust keeps its platform closed and raised an $80M Series B in February 2026 (secondary source).[81][81] Braintrust Series B SiliconANGLE Secondary
    • TruLens traces apps with OpenTelemetry, scores them with "feedback functions" and ships a Snowflake Cortex provider.[82][82] TruLens README Primary
    • LangWatch Scenario combines a description, the agents and a script of turns and checks. It calls the agent through its public interface and mocks tools, databases and APIs for offline runs.[83][83] Scenario README LangWatch Primary

    Trace-and-eval platforms.

    • Langfuse stores traces, sessions, datasets, experiments, judge scores and human annotation queues. It versions a dataset on every change. Self-hosting runs on PostgreSQL, Redis, ClickHouse and S3.[84][84] Self-hosting docs Langfuse Primary It accepts OpenTelemetry traces directly.[85][85] llms.txt Langfuse Primary
    • MLflow adds mlflow.genai.evaluate() with scorers, judges and tracing.[86][86] Comparing evaluation runs MLflow Primary
    • Opik runs on ClickHouse, MySQL, Redis and MinIO with a Helm chart, and keeps its whole code base under Apache-2.0.[87][87] Self-host architecture Opik Primary
    • Arize Phoenix traces with OpenInference. The server and phoenix-evals use the Elastic License 2.0; the client and OpenTelemetry packages use Apache-2.0.[88][88] LICENSE Arize Phoenix Primary
    • W&B Weave traces functions with @weave.op. The repo holds only the SDK and server bindings. Self-managed Weave runs inside W&B Self-Managed with ClickHouse, and CoreWeave hosts the docs.[89][89] Weave self-managed docs CoreWeave Primary
    • Evidently offers over 100 metrics, test suites and reports; its last push dates from late September 2026.[66][66] Evidently GitHub Primary Agenta combines a prompt playground, evaluation and observability.[90][90] LICENSE Agenta Primary Kiln keeps its core library MIT, but its desktop app uses a fair-code licence.[91][91] Kiln README Primary

Eval environments and RL training environments merged into one layer

An environment gives an agent a world to act in. It holds tools, data and rules, and it scores what the agent does. In 2026 the same environment often serves for evaluation and for RL training.

OpenEnv offers one step API for any environment. It exposes reset(), step() and state() over a WebSocket, and each environment is a Docker image.[106][106] OpenEnv README Primary A twelve-member technical committee now governs it, including Meta-PyTorch, Hugging Face, Nvidia, Microsoft and Modal. Version 0.12.0 shipped on 5 November 2026.[94][94] OpenEnv GitHub API Primary

verifiers links environments to training. Prime Intellect's library defines tasksets, harnesses and agents, and each rollout produces a trace.[108][108] verifiers overview Prime Intellect Primary A HarborTaskset loads Harbor tasks such as Terminal-Bench 2.[109][109] verifiers Harbor docs Prime Intellect Primary The library draws 762,000 PyPI downloads a month.[97][97] verifiers downloads pypistats Primary

The pieces mostly cooperate. Harbor defines tasks and sandboxes, and OpenEnv defines the step API and hosting. verifiers adds rubrics and training links, and Inspect adds logging and scoring. The story below follows one task through both uses.

One Agent Task Now Serves as a Test and as Training Data

How a single Harbor task flows through the shared open stack in 2026.

Step 1

Write the task

A Harbor folder: instruction.md, task.toml, environment/Dockerfile, optional solution, tests/test.sh.

ExampleA Terminal-Bench 2 task

Step 1 of 7: One stage: a task folder.

It starts as a small folder. A Harbor task holds an instruction, a Dockerfile and a test script. Harbor's 86 adapters turn existing benchmarks into this format.[32][32] create-task skill Harbor Primary[33][33] Adapters folder Harbor Primary
The Dockerfile becomes the world. OpenEnv starts it with reset(). The same image runs locally, on a cloud sandbox or as a Hugging Face Space.[106][106] OpenEnv README Primary
Any agent can act inside it. Harbor runs Claude Code, Codex or OpenHands. Environments expose their tools over MCP.[31][31] Harbor README Primary[106][106] OpenEnv README Primary
The task grades itself. The test script checks the final state. verifiers can add a rubric on top.[108][108] verifiers overview Prime Intellect Primary
Every step is kept. Inspect logs the run, and the OpenEnv–Harbor integration keeps the exact tokens for RL.[106][106] OpenEnv README Primary[149][149] Inspect eval logs docs UK AISI Primary
Use one: the score becomes an eval result. Terminal-Bench 2.0 uses Harbor as its official harness.[31][31] Harbor README Primary
Use two: the same rollout trains a model. OpenEnv connects to TRL, Unsloth, SkyRL and ART. verifiers links to Prime Intellect's prime-rl trainer.[106][106] OpenEnv README Primary[107][107] verifiers README Prime Intellect Primary

Figure 6. Harbor defines the task and sandbox, OpenEnv the step API, verifiers the rubrics and training links, Inspect the logs. Names are examples from each project's docs.

Source: Harbor, OpenEnv, verifiers and Inspect docs (5 Nov 2026).[31][31] Harbor README Primary[32][32] create-task skill Harbor Primary[106][106] OpenEnv README Primary[108][108] verifiers overview Prime Intellect Primary[109][109] verifiers Harbor docs Prime Intellect Primary[149][149] Inspect eval logs docs UK AISI Primary

Four Open Projects Join Evaluation and Training

Each project owns one part of the shared layer, and each imports the others.

  • Tasks and sandboxes

    Harbor

    86 benchmark adapters

    • Apache-2.0 · 6,821 stars
    • 4.8M monthly PyPI downloads
    • Official harness for Terminal-Bench 2.0
  • Step API and hosting

    OpenEnv

    40+ ready-made environments

    • BSD-3-Clause · 2,833 stars
    • 12-member technical committee
    • v0.12.0 on 5 Nov 2026
  • Rubrics and training

    verifiers

    762k monthly PyPI downloads

    • MIT · 4,768 stars
    • Loads Harbor tasks
    • 400+ Hub environments claimed (Oct 2025, unverified)
  • Logging and scoring

    Inspect AI

    200+ ready-made evaluations

    • MIT · 3,185 stars
    • OpenEnv evaluates with Inspect
    • Petri now runs natively on Inspect
Figure 7. Each project owns one part of the shared layer, and each imports the others. Prime Intellect's Hub count is a company claim from October 2025; no primary source gives a current count. Source: project READMEs, GitHub API and pypistats (5 Nov 2026); Prime Intellect post (Oct 2025).[21][21] Inspect AI README UK AISI Primary[33][33] Adapters folder Harbor Primary[94][94] OpenEnv GitHub API Primary[97][97] verifiers downloads pypistats Primary[106][106] OpenEnv README Primary[110][110] Post on X Prime Intellect Single source

Simulated users are maturing in two places. Sierra's tau2-bench v2.0 tests customer-service agents in six languages and full-duplex voice. Its text and voice sets hold 900 tasks each.[111][111] tau2-bench README Sierra Primary Meridian Labs' Petri runs an auditing agent against a target model and scores transcripts with a rubric.[117][117] Petri README Meridian Labs Primary

  • ProjectMaintainerLicenceStarsMonthly downloadsStatusBest for
    OpenEnv[94][94] OpenEnv GitHub API PrimaryOpenEnv technical committee (Meta-PyTorch, Hugging Face and others)BSD-3-Clause2,83349k[95][95] openenv downloads pypistats PrimaryVery active, v0.12.0 on 5 Nov 2026One step API for any environment
    verifiers[96][96] verifiers GitHub PrimaryPrime IntellectMIT4,768762k[97][97] verifiers downloads pypistats PrimaryVery activeRL and eval environments, Environments Hub
    community-environments[98][98] community-environments GitHub PrimaryPrime IntellectApache-2.0264n/aActiveShared environment library
    tau2-bench[99][99] tau2-bench GitHub PrimarySierraMIT2,403n/aVery active, v2.0.0 in Oct 2026Customer-service agents, text and voice
    AppWorld[100][100] AppWorld GitHub PrimaryStony Brook NLPApache-2.0548662k (CI-heavy)[101][101] appworld downloads pypistats PrimaryActiveApps, APIs and coding agents
    BrowserGym[102][102] BrowserGym GitHub PrimaryServiceNow ResearchApache-2.01,42714kActiveWeb agents
    AgentLab[103][103] AgentLab GitHub PrimaryServiceNow ResearchApache-2.0661n/aActiveLarge parallel web-agent runs
    OSWorld[104][104] OSWorld GitHub PrimaryXLANG Lab (HKU)Apache-2.03,251n/aActive, no release since 2024Desktop computer-use agents
    Petri[105][105] inspect_petri GitHub API PrimaryMeridian LabsMIT1,40248kVery activeAlignment audits with an auditor agent
    Table 4. GitHub API and pypistats, 5 Nov 2026.
    • OpenEnv. Farama's Gymnasium inspired the design. A Harbor integration runs Claude Code, Codex and other agents on Harbor tasks. OpenEnv scores with rubrics and evaluates with Inspect AI. The repo moved from meta-pytorch to its own openenv organisation. Committee members also include Prime Intellect and Unsloth.[106][106] OpenEnv README Primary
    • verifiers. A harness is the program that runs the model; an agent combines a harness, a model and a runtime policy. Toolsets install as MCP servers.[108][108] verifiers overview Prime Intellect Primary It links to the Environments Hub, prime-rl and hosted training.[107][107] verifiers README Prime Intellect Primary
    • tau2-bench. Covers airline, retail and telecom. A live leaderboard runs at taubench.com. Harbor ships a tau3-bench adapter, but no separate tau3 repo exists yet.[111][111] tau2-bench README Sierra Primary
    • AppWorld. A controllable world of apps and people for function-calling and coding agents; ACL 2024 best resource paper.[112][112] AppWorld README Stony Brook NLP Primary
    • BrowserGym and AgentLab. BrowserGym bundles MiniWoB, WebArena, VisualWebArena, WorkArena and AssistantBench.[113][113] BrowserGym README ServiceNow Primary AgentLab runs large parallel experiments on it with Ray.[114][114] AgentLab README ServiceNow Primary Both repos warn that they are research tools, not consumer products.
    • OSWorld. Runs desktop agents in VMs on VMware, VirtualBox, Docker, AWS or Azure. OSWorld-Verified fixed community-reported issues in July 2025. The last tagged release dates from June 2024.[115][115] OSWorld README XLANG Lab Primary
    • ControlArena. UK AISI and Redwood Research built it for AI control experiments, where a red-team model tries to beat safety measures. MIT-licensed, 15 settings.[116][116] ControlArena repository Primary
    • Petri. Generates scenarios from seed instructions and simulates tools. It moved from Anthropic's safety-research organisation to Meridian Labs.[117][117] Petri README Meridian Labs Primary

Four open red-team tools lead, and their owners now matter as much as their features

Red-team tools attack a model or an agent on purpose. They look for jailbreaks, prompt injection, data leaks and unsafe tool use.

promptfoo has the widest plugin set and the most users. It holds 72 red-team plugin docs, including excessive agency, MCP attacks and memory poisoning.[124][124] Red-team plugins folder promptfoo Primary Domain packs cover insurance, finance and medicine. By default it generates attacks through a remote service, and its docs rate local generation quality as generally low.[125][125] Red-team configuration promptfoo Primary

garak and PyRIT suit code-driven testing. NVIDIA's garak combines probes, detectors and harnesses, and a REST generator connects it to any endpoint.[126][126] garak README NVIDIA Primary Microsoft's PyRIT composes single-turn, multi-turn and compound attacks in Python, over HTTP, WebSockets or Playwright.[128][128] PyRIT README Microsoft Primary DeepTeam lists over 50 vulnerabilities and scores them locally with LLM judges.[129][129] DeepTeam README Confident AI Primary

promptfoo Dwarfs the Other Open Red-Team Tools in Downloads

Monthly downloads on 5 November 2026. Square area is proportional to downloads.

3.6MpromptfooOpenAI · MIT · npm, whole package72kPyRITMicrosoft · MIT71kDeepTeamConfident AI ·Apache-2.039kgarakNVIDIA ·Apache-2.0

Area is proportional to monthly downloads

Data table
ItemValueNote
promptfoo3.6MOpenAI · MIT · npm, whole package
PyRIT72kMicrosoft · MIT
DeepTeam71kConfident AI · Apache-2.0
garak39kNVIDIA · Apache-2.0
Figure 8. promptfoo belongs to OpenAI, and its npm count covers the whole package, not only red teaming. Microsoft backs PyRIT, NVIDIA backs garak and Confident AI (venture-backed) builds DeepTeam. By scope, promptfoo documents 72 red-team plugins, garak ships 44 probe modules and DeepTeam lists over 50 vulnerabilities. DeepTeam's downloads show more activity than its last release (November 2025) suggests. Source: GitHub API, pypistats, npm and project docs (5 Nov 2026).[46][46] promptfoo GitHub Primary[47][47] promptfoo downloads npm Primary[118][118] garak GitHub Primary[119][119] garak downloads pypistats Primary[120][120] PyRIT GitHub Primary[121][121] pyrit downloads pypistats Primary[122][122] DeepTeam GitHub Primary[123][123] deepteam downloads pypistats Primary[124][124] Red-team plugins folder promptfoo Primary[127][127] garak probes folder NVIDIA Primary[129][129] DeepTeam README Confident AI Primary

Owners now shape the choice. OpenAI owns promptfoo, which may worry buyers who test competing models. Microsoft and NVIDIA back PyRIT and garak, so these two make the safest long-term bets for neutrality.

  • ProjectMaintainerLicenceStarsMonthly downloadsStatusBest for
    promptfoo redteam[46][46] promptfoo GitHub PrimaryOpenAIMIT26,875npm 3.6M (whole package)Very activeWidest plugin set, CI use
    garak[118][118] garak GitHub PrimaryNVIDIAApache-2.09,87239k[119][119] garak downloads pypistats PrimaryVery activeScanner for any REST endpoint
    PyRIT[120][120] PyRIT GitHub PrimaryMicrosoftMIT4,75572k[121][121] pyrit downloads pypistats PrimaryVery activeMulti-turn attacks composed in code
    DeepTeam[122][122] DeepTeam GitHub PrimaryConfident AIApache-2.03,08571k[123][123] deepteam downloads pypistats PrimaryActive, last release Nov 2025Red team on top of DeepEval
    Table 5. GitHub API, pypistats and npm, 5 Nov 2026.

    Neighbouring tools.

    • Giskard's giskard-scan covers injection, jailbreaks and harmful content.[77][77] OSS README Giskard Primary
    • AgentDojo from ETH Zurich measures indirect prompt injection with code-based checks.[130][130] AgentDojo GitHub Primary
    • Snyk's agent-scan checks local agent configs and MCP servers, but needs a Snyk token.[131][131] agent-scan README Snyk Primary
    • Lakera archived its PINT benchmark in April 2026.[132][132] PINT benchmark GitHub Primary
    • Singapore's Project Moonshot, an Apache-2.0 toolkit, remains in beta at version 0.7.6.[133][133] Project Moonshot repository Primary
    • OWASP's AI Testing Guide v1 gives a free test method for AI systems.[134][134] OWASP AI Testing Guide Primary OWASP's Top 10 for Agentic Applications names risks such as agent goal hijack and tool misuse.[135][135] Top 10 for Agentic Applications for 2026 OWASP Primary

OpenTelemetry won the transport, but the vocabulary and result formats remain open

OpenTelemetry carries traces in almost every eval platform. On top of it, attribute vocabularies, result formats and tool protocols are at different stages.

OTLP ingestion became normal. Langfuse, MLflow, promptfoo, TruLens and DeepEval all accept or export OpenTelemetry traces. Two attribute vocabularies compete on top of the transport.

OpenInference leads in practice. Arize's vocabulary draws 8.6 million monthly downloads.[138][138] OpenInference conventions downloads pypistats Primary It instruments the OpenAI Agents SDK, the Claude Agent SDK, LangChain and AutoGen, and ships a bridge for OpenLLMetry.[147][147] OpenInference README Primary The vocabularies therefore seem to converge.

The official GenAI conventions are still a draft. They moved out of the core OpenTelemetry repo in 2026 and cover inference, retrieval, agent spans and MCP.[141][141] Core GenAI README OpenTelemetry Primary[142][142] GenAI conventions overview OpenTelemetry Primary Their status stays "Development", and the schema URL section still reads "TODO".

Three trace vocabularies on top of OpenTelemetry

StandardMaintainerLicenceAdoption signalStatus
OTel GenAI semantic conventions[136][136] OTel GenAI conventions GitHub API PrimaryOpenTelemetryApache-2.0523 stars; new repo since May 2026"Development", no release yet
OpenInference[137][137] OpenInference GitHub PrimaryArize (Dynatrace)Apache-2.01,305 stars; 8.6M monthly downloads[138][138] OpenInference conventions downloads pypistats PrimaryActive, widest instrumentation
OpenLLMetry[139][139] OpenLLMetry GitHub PrimaryTraceloop (ServiceNow)Apache-2.07,522 stars; 1.8M monthly downloads[140][140] traceloop-sdk downloads pypistats PrimaryActive, release on 5 Nov 2026
Table 6. Two of the three vocabularies now belong to companies bought in 2026. The neutral one has no release yet. Source: GitHub API and pypistats (5 Nov 2026).[136][136] OTel GenAI conventions GitHub API Primary[137][137] OpenInference GitHub Primary[138][138] OpenInference conventions downloads pypistats Primary[139][139] OpenLLMetry GitHub Primary[140][140] traceloop-sdk downloads pypistats Primary

A neutral slot for eval scores now exists. The gen_ai.evaluation.result event carries a name, a score, a label and an explanation on the evaluated span.[145][145] GenAI events OpenTelemetry Primary It is the first neutral way to put eval scores on production traces. Judge model, rubric version and confidence intervals still need custom attributes.

No result format has won. Inspect writes binary .eval logs, about one eighth the size of JSON, with access to single samples.[149][149] Inspect eval logs docs UK AISI Primary Many projects read or export this format, so it acts as the richest de facto format. The neutral alternative barely registers.

The two candidate result formats

FeatureInspect .eval logs (UK AISI)Every Eval Ever (EvalEval Coalition)
FormatBinary .eval files, default since v0.3.46Shared schema, instance-level JSONL
SizeAbout 1/8 the size of JSONNot stated
Single-sample accessYesYes
Agentic samples with tool callsYesYes
Shared results databaseNoCrowdsourced database
Reads other harnessesMany projects read or export itConverters for Inspect, HELM, lm-eval
Cloud storageS3 or AzureNot stated
Uptake signalRichest de facto format285 PyPI downloads last month
Table 7. Inspect logs win by use; Every Eval Ever offers a neutral schema with converters but very low uptake. Source: Inspect eval-logs docs; Every Eval Ever README; pypistats (5 Nov 2026).[149][149] Inspect eval logs docs UK AISI Primary[150][150] Every Eval Ever README EvalEval Primary[151][151] every-eval-ever downloads pypistats Primary

285

PyPI downloads last month for Every Eval Ever, the neutral eval result schema. Inspect AI drew 2.9 million.

Source: pypistats (5 Nov 2026).[151][151] every-eval-ever downloads pypistats Primary[3][3] inspect-ai downloads pypistats Primary

ClickHouse became the default trace store. Langfuse, Opik and self-managed Weave all run on it.[84][84] Self-hosting docs Langfuse Primary[87][87] Self-host architecture Opik Primary[89][89] Weave self-managed docs CoreWeave Primary ClickHouse also bought Langfuse in January 2026. Datasets mostly live on Hugging Face, and Langfuse versions its datasets on every change.[148][148] Datasets docs Langfuse Primary

MCP became the common way for eval agents to reach tools. Inspect, verifiers, OpenEnv, Harbor and promptfoo all support MCP tools. The spec has five dated versions, from November 2024 to July 2026.[152][152] Schema folder MCP Primary The project is moving from MIT to Apache-2.0 for code and spec.[153][153] LICENSE MCP Primary

    • Agent spans. The GenAI conventions define create_agent, invoke_agent and invoke_workflow. The last fits apps that define their own control flow, such as LangGraph.[144][144] GenAI agent spans OpenTelemetry Primary
    • Core conventions. The core OpenTelemetry semantic conventions repo reached v1.45.0 on 2 November 2026.[143][143] Semantic conventions releases OpenTelemetry Primary
    • OpenInference span kinds. Every span needs a kind, such as LLM, TOOL, AGENT, GUARDRAIL or EVALUATOR.[146][146] Semantic conventions OpenInference Primary
    • MCP spans. OpenTelemetry adds span conventions for MCP calls.[154][154] MCP conventions OpenTelemetry Primary promptfoo ships an MCP red-team plugin.
    • MCP licence. Docs move to CC-BY-4.0, code and spec to Apache-2.0.[153][153] LICENSE MCP Primary
    • Datasets. lm-evaluation-harness and SWE-bench load tasks from Hugging Face Datasets.

Docker is the sandbox contract, but judges and statistics still lack standards

Three supporting layers decide how far readers can trust a result. They cover where the agent runs, who grades it and how sure the number is.

Docker became the universal sandbox contract. Inspect ships Docker and local sandboxes, and external packages add Kubernetes, Daytona, Modal, EC2 and Proxmox.[155][155] Inspect sandboxing docs UK AISI Primary Harbor runs on nine cloud back ends, and OpenEnv runs each environment as a Docker image. Cloud vendors now compete as interchangeable back ends.

Check Daytona's licence before you build on it. Daytona has 71,377 GitHub stars, but the GitHub API reports no licence, and our research did not confirm one.[159][159] Daytona GitHub Primary

Most harnesses call models through an OpenAI-compatible API. vLLM serves open models behind that API, with over 96,000 stars under Apache-2.0.[160][160] vLLM GitHub Primary Teams can serve open judge models through vLLM to cut grading costs.

LLM judges now grade most open-ended answers. Every framework ships judge templates, and open guard models give a cheaper option.[161][161] Granite Guardian 4.1 8B model card IBM Primary[162][162] Qwen3Guard models Hugging Face API Primary[163][163] Llama Guard 4 model card Meta Primary No open judge publishes human agreement on agent transcripts in a regulated domain. Most published numbers compare judges with GPT-4-class labels, not with human experts.

Open judge and guard models

ModelMaintainerLicenceSignalNote
Granite Guardian 4.1 8B[161][161] Granite Guardian 4.1 8B model card IBM PrimaryIBMApache-2.010k downloads in 30 daysCustom criteria, groundedness, function-call checks
Qwen3Guard[162][162] Qwen3Guard models Hugging Face API PrimaryAlibabaApache-2.0223k downloads (0.6B size)Safety in 119 languages
Llama Guard 4 12B[163][163] Llama Guard 4 model card Meta PrimaryMetaLlama 4 Community License88k downloadsMLCommons hazard taxonomy
Table 8. Hugging Face download counts, November 2026. None of these models publishes human agreement on agent transcripts in a regulated domain. Source: model cards and Hugging Face API.[161][161] Granite Guardian 4.1 8B model card IBM Primary[162][162] Qwen3Guard models Hugging Face API Primary[163][163] Llama Guard 4 model card Meta Primary

Averaging judges is a cheap gain. Composo found that averaging eight judge scores added 9.8 points on RewardBench 2. Three scores gave most of that gain.[164][164] Judge ensembling paper Composo Primary

Statistics remain the weakest layer. Most CI gates still compare a pass rate with a fixed threshold. Inspect offers the best single-run intervals and supports early stopping.[29][29] Inspect metrics docs UK AISI Primary[165][165] Inspect early stopping docs UK AISI Primary MLflow alone ships a paired test.[86][86] Comparing evaluation runs MLflow Primary No tool combines paired tests, non-inferiority margins and monitoring over time.

How Many Test Cases Does a Trustworthy Pass Rate Need?

Move the sliders. Most CI gates compare one pass rate with a threshold and never show this margin.

test cases needed

683

independent test cases for a 95% interval

1.96² × 0.80 × 0.20 × 1.0 ÷ 0.030² = 683

Cases needed (log scale) by margin of error, in points

n = 1.96² × p × (1 − p) × design effect ÷ margin². A pass rate near 80%, measured to ±3 points, needs about 683 independent cases.

Figure 9. Normal approximation for a pass rate at 95% confidence. It assumes independent test cases; the design effect inflates the count when several cases share one scenario. An illustration, not tied to any one tool. Source: standard sample-size formula for a proportion; our illustration.

Which tools ship which statistics

ToolSingle-run intervalsJudge agreementSequential / early stoppingPaired testItem-response modelNon-inferiority marginDrift over time
Inspect AIYes: stderr, bootstrap, Wilson, clusteredYes: Krippendorff's alphaYesNon/aNoNo
MLflow 3.18Yes: bootstrapn/an/aYes: McNemar, Wilcoxonn/aNoNo
NeMo EvaluatorYes: via scipyn/an/aNon/aNoNo
Epoch AI ECIn/an/an/an/aYes: Bayesian IRTNoNo
Typical CI gate (most app eval tools)No: pass rate vs thresholdNoNoNoNoNoNo
Table 9. Single-run intervals are common, paired tests are rare, and non-inferiority margins and drift monitoring are missing everywhere. Source: Inspect metrics and early-stopping docs; MLflow docs; NeMo Evaluator README; Epoch AI ECI package.[26][26] NeMo Evaluator README NVIDIA Primary[29][29] Inspect metrics docs UK AISI Primary[38][38] Capabilities Index package Epoch AI Primary[86][86] Comparing evaluation runs MLflow Primary[165][165] Inspect early stopping docs UK AISI Primary
  • ProjectMaintainerLicenceStarsStatusRole
    E2B[156][156] E2B GitHub PrimaryE2BApache-2.014,721Very activeCloud sandboxes for agents
    gVisor[157][157] gVisor GitHub PrimaryGoogleApache-2.019,875ActiveStrong container isolation
    Modal client[158][158] Modal client GitHub PrimaryModalApache-2.0 (client only)533ActiveServerless sandboxes, closed platform
    Daytona[159][159] Daytona GitHub PrimaryDaytonanot reported by the API71,377Last push 24 Jul 2026Cloud sandboxes for agents
    Table 10. GitHub API, 5 Nov 2026.

    Harbor's back ends: local Docker, Daytona, Modal, LangSmith, Blaxel, Novita, Tensorlake, Runta and Sail.[31][31] Harbor README Primary The lm-evaluation-harness README recommends vLLM's server for large models. OpenCompass added a LiteLLM gateway in 2026.[37][37] OpenCompass README Primary

Larger companies bought most eval platforms in 2026, and no open licence changed

2026 was the consolidation year for eval and observability tools. Data platforms, observability vendors, security vendors and model labs bought most independent players.

Seven deals touched open eval projects between January and October 2026. ClickHouse bought Langfuse on 16 January.[168][168] Langfuse acquisition ClickHouse Vendor OpenAI bought promptfoo, ServiceNow bought Traceloop, and Cisco closed Galileo in May.[73][73] Joining OpenAI promptfoo Vendor[170][170] Joining ServiceNow Traceloop Vendor[171][171] Galileo acquisition Cisco Vendor Dynatrace closed its purchase of Arize, the owner of Phoenix, on 1 October.[175][175] Dynatrace completes Arize deal engineering.com Secondary

Platforms, Security Vendors and Labs Bought the Eval Tools

Deals for eval, observability and AI-security tools, June 2025 to October 2026, by type of buyer. Bold: the four 2026 data-platform deals.

Jul ’25OctJan ’26AprJulOctNowLargest price: $915MData and observability platformsCisco closes Galileo Becomes Splunk AgentObservability ServiceNow buysTraceloop OpenLLMetry staysopen ClickHouse buysLangfuse Core stays MIT Dynatrace closesArize (Phoenix) $915M reported Security vendorsA10 Networks buysTrojAI Palo Alto Networkscloses Portkey AI gateway of PrismaAIRS Check Point buysDeepchecks team andIP Up to $20M (pressestimate) Zscaler buys SPLX Check Point buysLakera Snyk buys InvariantLabs Model labsOpenAI buyspromptfoo Closed; stays MIT Humanloop team joinsAnthropic Team move, not acompany purchase Other buyersMintlify buysHelicone Hosted product inmaintenance Beacon Software buysHaize Labs Software roll-up
Data table
DateLaneEventKindNote
2025-06Security vendorsSnyk buys Invariant Labsacquired
2025-08Model labsHumanloop team joins AnthropicacquiredTeam move, not a company purchase
2025-09Security vendorsCheck Point buys Lakeraacquired
2025-11Security vendorsZscaler buys SPLXacquired
2026-01-16Data and observability platformsClickHouse buys LangfuseacquiredCore stays MIT
2026-03Data and observability platformsServiceNow buys TraceloopacquiredOpenLLMetry stays open
2026-03-03Other buyersMintlify buys HeliconeacquiredHosted product in maintenance
2026-03-09Model labsOpenAI buys promptfooacquiredClosed; stays MIT
2026-05Security vendorsCheck Point buys Deepchecks team and IPacquiredUp to $20M (press estimate)
2026-05-22Data and observability platformsCisco closes GalileoacquiredBecomes Splunk Agent Observability
2026-05-29Security vendorsPalo Alto Networks closes PortkeyacquiredAI gateway of Prisma AIRS
2026-06-15Security vendorsA10 Networks buys TrojAIacquired
2026-09Other buyersBeacon Software buys Haize LabsacquiredSoftware roll-up
2026-10-01Data and observability platformsDynatrace closes Arize (Phoenix)acquired$915M reported
Figure 10. Dates are announcement or close dates as given. Earlier deals in AI security set the pattern for the 2026 eval-tool deals. CoreWeave also owns W&B and hosts the Weave docs. Source: buyer and target announcements; press reports.[73][73] Joining OpenAI promptfoo Vendor[168][168] Langfuse acquisition ClickHouse Vendor[169][169] Helicone acquisition Mintlify Vendor[170][170] Joining ServiceNow Traceloop Vendor[171][171] Galileo acquisition Cisco Vendor[172][172] Portkey acquisition Palo Alto Networks Vendor[173][173] Arize acquisition Dynatrace Vendor[176][176] Invariant Labs acquisition Snyk Vendor[177][177] Lakera acquisition Check Point Vendor[178][178] Zscaler and SPLX Help Net Security Secondary[179][179] Humanloop team joins Anthropic Data Phoenix Secondary[180][180] Check Point and Deepchecks Security Boulevard Secondary[181][181] TrojAI acquisition A10 Networks Vendor[182][182] Beacon Software and Haize Labs Osler Secondary

Buyers fall into three groups. ClickHouse, Dynatrace, Cisco with Splunk, and ServiceNow wanted traces and evals for their platforms. Palo Alto Networks, Check Point, Zscaler, A10 Networks and Snyk wanted AI security tools. OpenAI bought promptfoo, and Anthropic took the Humanloop team.[179][179] Humanloop team joins Anthropic Data Phoenix Secondary

Most prices stayed private. Dynatrace paid a reported $915M for Arize, about $815M of it in cash.[173][173] Arize acquisition Dynatrace Vendor[174][174] Dynatrace and Arize ITPro Secondary Calcalist reported $60–80M for Traceloop, but nobody confirmed it.[183][183] Traceloop price Calcalist Single source Press estimates put the Deepchecks price at up to $20M.[184][184] Deepchecks price Dealroom citing Calcalist Estimate

Ownership changed, but licences did not. No eval project in scope moved to a BSL or AGPL licence in 2025 or 2026. No acquirer changed an open licence after a deal. promptfoo stays MIT under OpenAI, and Langfuse's core stays MIT under ClickHouse.[74][74] promptfoo README Primary[168][168] Langfuse acquisition ClickHouse Vendor

Most Eval Code Can Be Hosted for Others; Phoenix Cannot

What each licence lets a team do with the code, November 2026. A reading of licence files, not legal advice.

Project (licence)Use internally Change the code Embed and redistribute Host as a service for others
Inspect AI, lm-eval, promptfoo, PyRIT MIT Allowed Allowed Allowed Allowed
Harbor, DeepEval, Opik, MLflow, garak Apache-2.0 Allowed Allowed Allowed Allowed
OpenEnv BSD-3-Clause Allowed Allowed Allowed Allowed
verifiers, tau2-bench, Giskard, Scenario MIT or Apache-2.0 Allowed Allowed Allowed Allowed
Langfuse, Agenta MIT core + closed ee/ Allowed With limits core only With limits core only With limits license ee/ features
Change the code: core onlyEmbed and redistribute: core onlyHost as a service for others: license ee/ features
LangWatch Apache core + enterprise/ Allowed With limits core only With limits core only With limits SSO, audit logs, billing closed
Change the code: core onlyEmbed and redistribute: core onlyHost as a service for others: SSO, audit logs, billing closed
Arize Phoenix server, phoenix-evals Elastic License 2.0 Allowed With limits within ELv2 terms With limits client + OTel packages are Apache-2.0 Not allowed no hosted or managed service
Change the code: within ELv2 termsEmbed and redistribute: client + OTel packages are Apache-2.0Host as a service for others: no hosted or managed service
Kiln desktop app Fair-code (library MIT) With limits read terms With limits read terms With limits read terms With limits read terms before commercial use
Use internally: read termsChange the code: read termsEmbed and redistribute: read termsHost as a service for others: read terms before commercial use
LangSmith, Braintrust, Weave server, Modal Open SDK, closed platform With limits SDK; back end is paid With limits SDK only With limits SDK only Not allowed
Use internally: SDK; back end is paidChange the code: SDK onlyEmbed and redistribute: SDK only
MCP MIT → Apache-2.0 Allowed Allowed Allowed Allowed
Daytona No licence reported Unknown or not applicable Unknown or not applicable Unknown or not applicable Unknown or not applicable check before building
Host as a service for others: check before building

What to notice

  • Read the shaded column: Phoenix's Elastic License is the only open licence here that forbids hosting.
Figure 11. Permissive projects allow everything, including hosting for others. Open-core projects allow the core but license the enterprise parts. Phoenix's Elastic License forbids offering it as a hosted or managed service. This is a reading of licence files, not legal advice. Source: project LICENSE files and READMEs (5 Nov 2026).[88][88] LICENSE Arize Phoenix Primary[90][90] LICENSE Agenta Primary[91][91] Kiln README Primary[153][153] LICENSE MCP Primary[159][159] Daytona GitHub Primary[166][166] LICENSE Langfuse Primary[167][167] Enterprise LICENSE LangWatch Primary

Evals now sit inside bigger suites. Buyers should expect roadmaps to bend toward the parent platform. Several projects also moved home without a sale: Harbor, OpenEnv, Petri and Ragas changed GitHub organisations.

Venture Money Backs Most of the Remaining Independents

Thirteen open eval projects and companies that no acquirer owns, by type of backer, November 2026. One square is one project.

  • 7 projects Venture capital
  • 3 projects Governments and nonprofits
  • 3 projects Large labs and tech firms

Each square is 1 of 13 projects.

Data table
GroupValue
Venture capital7 projects
Governments and nonprofits3 projects
Large labs and tech firms3 projects
Figure 12. Governments and nonprofits: Inspect AI (UK AISI), inspect_evals (Generality Labs), Every Eval Ever (EvalEval Coalition). Large labs and tech firms: garak (NVIDIA), PyRIT (Microsoft), OpenEnv (Meta-PyTorch and committee). Venture capital: Confident AI, Comet, Braintrust, LangChain, Agenta, LangWatch, Giskard. Each backer brings its own risk: public budgets, lab priorities or the next funding round. Source: project READMEs and funding announcements (5 Nov 2026).[21][21] Inspect AI README UK AISI Primary[81][81] Braintrust Series B SiliconANGLE Secondary[118][118] garak GitHub Primary[120][120] PyRIT GitHub Primary[106][106] OpenEnv README Primary[150][150] Every Eval Ever README EvalEval Primary
  • DateTargetBuyerEffect on the open project
    16 Jan 2026Langfuse[168][168] Langfuse acquisition ClickHouse VendorClickHouseCore stays MIT, cloud continues
    3 Mar 2026Helicone[169][169] Helicone acquisition Mintlify VendorMintlifyHosted product in maintenance mode
    9 Mar 2026 (now closed)promptfoo[73][73] Joining OpenAI promptfoo VendorOpenAIStays open source under MIT[74][74] promptfoo README Primary
    Mar 2026Traceloop (OpenLLMetry)[170][170] Joining ServiceNow Traceloop VendorServiceNowOpenLLMetry stays open, joins AI Control Tower
    22 May 2026 (close)Galileo[171][171] Galileo acquisition Cisco VendorCiscoBecomes Splunk Agent Observability
    29 May 2026 (close)Portkey[172][172] Portkey acquisition Palo Alto Networks VendorPalo Alto NetworksBecomes the AI gateway of Prisma AIRS
    1 Oct 2026 (close)Arize (Phoenix)[173][173] Arize acquisition Dynatrace VendorDynatracePhoenix and AX continue, reported $915M[174][174] Dynatrace and Arize ITPro Secondary[175][175] Dynatrace completes Arize deal engineering.com Secondary
    Table 11. 2026 deals that touched open eval projects.
    Licence modelProjectsWhat you can do
    Permissive (MIT, Apache-2.0, BSD)Inspect, lm-evaluation-harness, Harbor, promptfoo, DeepEval, DeepTeam, Opik, MLflow, garak, PyRIT, verifiers, OpenEnv, tau2-bench, Giskard, ScenarioUse, change, embed and host as a service
    Open core with closed ee/ folderLangfuse, Agenta, LangWatchUse the MIT or Apache core freely, but license the enterprise parts
    Source-available (Elastic License 2.0)Phoenix server and phoenix-evalsUse internally, but do not offer it as a hosted service
    Fair-codeKiln desktop appRead the terms before commercial use
    Open SDK, closed platformLangSmith, Braintrust, Weave server, ModalUse the SDK, but the back end stays a paid product
    Licence in transitionMCP, from MIT to Apache-2.0Expect more permissive terms
    Table 12. Licence models across the eval stack.

    Guidance for hosted offers. A team that wants to host evals for others should prefer the permissive projects. It should avoid hosting Phoenix as a service.[88][88] LICENSE Arize Phoenix Primary It should keep Langfuse and LangWatch enterprise features out of any hosted offer without a licence.[166][166] LICENSE Langfuse Primary[167][167] Enterprise LICENSE LangWatch Primary

    Earlier and smaller deals. CoreWeave now owns W&B and hosts the Weave docs.[89][89] Weave self-managed docs CoreWeave Primary Check Point bought the Deepchecks team and IP in 2026.[180][180] Check Point and Deepchecks Security Boulevard Secondary Dynatrace paid about $815M of the $915M in cash and the rest in replacement equity.[173][173] Arize acquisition Dynatrace Vendor

Standardise on the plumbing; results, judges and statistics are still open ground

The table sums up what a team can treat as settled today and what still moves.

The lower layers are safe to standardise on. Docker, OpenAI-compatible APIs, OpenTelemetry and MCP will likely stay.

The harness choice depends on the job. Inspect suits agentic and safety work, lm-evaluation-harness suits open weights, and Harbor suits container tasks.

The upper layers still lack standards. Result formats, judge validation and contract-grade statistics remain open. Lab-owned red-team tools also raise a neutrality question.

Standard today, still open

AreaStandard todayStill open
Model benchmarksInspect and lm-evaluation-harnessFunding for leaderboards and static benchmarks
Agent tasksHarbor folder with Dockerfile and test scriptCost and speed of large container runs
Environment APIOpenEnv reset, step, stateSize and quality of shared hubs
SandboxesDocker imagesIsolation standards and vendor choice
Tool accessMCPFinal licence and versioning
Trace transportOpenTelemetry OTLPNone
Trace vocabularyOpenInference in practiceOTel GenAI conventions still "Development"
Eval results on tracesgen_ai.evaluation.result eventJudge, rubric and interval metadata
Result exchangeInspect .eval logs in practiceEvery Eval Ever uptake
JudgesLLM judges in every frameworkHuman agreement data for agent transcripts
StatisticsThreshold gates and single-run intervalsPaired tests, non-inferiority and drift over time
Red teampromptfoo, garak, PyRITNeutrality of lab-owned tools
Table 13. Only trace transport has nothing left open. Every layer above the harness has at least one gap. Source: this chapter, based on project repositories and docs (5 Nov 2026).

Sources

Every number keeps its date and source. Badges mark source quality: primary, secondary, vendor (a claim about the publisher's own product), single source, or estimate.

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    create-task skill, Harbor. It defines the task folder layout. Primary github.com
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    Adapters folder, Harbor. It holds the 86 benchmark adapters. Primary github.com
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    lighteval README, Hugging Face. It claims over 1,000 tasks. Primary github.com
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    OpenCompass README. It lists the 2026 news, including AgentCompass. Primary github.com
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    Capabilities Index package, Epoch AI. It describes the Bayesian item-response fit. Primary github.com
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    HELM README, Stanford CRFM. It states the start of maintenance mode. Primary github.com
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    Maintenance mode policy, HELM. It explains what the team still maintains. Primary crfm-helm.readthedocs.io
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    simple-evals README, OpenAI. It announces the end of updates in July 2025. Primary github.com
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    Evals README, OpenAI. It points users to the OpenAI Dashboard. Primary github.com
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    HAL harness README, Princeton PLI. It states that the repo stays archived for reference. Primary github.com
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    End of the Open LLM Leaderboard, Hugging Face. It announces the retirement on 13 March 2025. Primary huggingface.co
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    Leaderboards docs, Hugging Face. It describes the Open LLM Leaderboard in the past tense. Primary huggingface.co
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    promptfoo, GitHub. It gives stars, licence and release data. Primary github.com
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    promptfoo downloads, npm. It gives the monthly npm download count. Primary api.npmjs.org
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    DeepEval, GitHub. It gives stars, licence and push data. Primary github.com
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    deepeval downloads, pypistats. It gives the monthly PyPI download count. Primary pypistats.org
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    Ragas, GitHub. It gives stars, licence and the last push. Primary github.com
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    Giskard, GitHub. It gives stars, licence and release data. Primary github.com
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    openevals, GitHub. It gives stars, licence and release data. Primary github.com
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    agentevals, GitHub. It gives stars, licence and push data. Primary github.com
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    autoevals, GitHub. It gives stars, licence and release data. Primary github.com
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    autoevals downloads, pypistats. It gives the monthly PyPI download count. Primary pypistats.org
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    TruLens, GitHub. It gives stars, licence and release data. Primary github.com
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    LangWatch Scenario, GitHub. It gives stars, licence and release data. Primary github.com
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    Langfuse, GitHub. It gives stars, licence and release data. Primary github.com
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    langfuse downloads, pypistats. It gives the monthly PyPI download count. Primary pypistats.org
  60. [60]
    MLflow, GitHub. It gives stars, licence and push data. Primary github.com
  61. [61]
    mlflow downloads, pypistats. It gives the monthly PyPI download count. Primary pypistats.org
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    Opik, GitHub. It gives stars, licence and release data. Primary github.com
  63. [63]
    opik downloads, pypistats. It gives the monthly PyPI download count. Primary pypistats.org
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    Arize Phoenix, GitHub. It gives stars, licence and release data. Primary github.com
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    W&B Weave, GitHub. It gives stars, licence and release data. Primary github.com
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    Evidently, GitHub. It gives stars, licence and the last push. Primary github.com
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    Agenta, GitHub. It gives stars and release data. Primary github.com
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    Kiln, GitHub. It gives stars and push data. Primary github.com
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    HTTP provider docs, promptfoo. It describes calls to any HTTP endpoint. Primary github.com
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    GitHub Action docs, promptfoo. It describes the before-and-after comparison. Primary github.com
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    Joining OpenAI, promptfoo. It announces the deal and the user claims. Vendor promptfoo.dev
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    promptfoo README. It states that Promptfoo now belongs to OpenAI and stays MIT-licensed. Primary github.com
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    agentevals README, LangChain. It describes trajectory judges and match modes. Primary github.com
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    Braintrust Series B, SiliconANGLE. It reports the $80M round, as a secondary source. Secondary siliconangle.com
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    TruLens README. It describes OpenTelemetry tracing and feedback functions. Primary github.com
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    Scenario README, LangWatch. It describes scenarios, simulated users and judges. Primary github.com
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    llms.txt, Langfuse. It lists the OpenTelemetry endpoint and the docs. Primary langfuse.com
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    Comparing evaluation runs, MLflow. It describes the paired tests between two runs. Primary github.com
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    Self-host architecture, Opik. It lists ClickHouse, MySQL, Redis and MinIO. Primary github.com
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    LICENSE, Arize Phoenix. It sets the Elastic License 2.0 terms. Primary github.com
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    Weave self-managed docs, CoreWeave. It describes Weave on ClickHouse under CoreWeave. Primary docs.coreweave.com
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    LICENSE, Agenta. It puts the ee/ folder under separate terms. Primary github.com
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    Kiln README. It describes the MIT library and the fair-code app. Primary github.com
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    CI/CD docs, promptfoo. It describes exit-code gates. Primary github.com
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    OpenEnv, GitHub API. It gives stars, licence and the move from meta-pytorch. Primary api.github.com
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    openenv downloads, pypistats. It gives the monthly PyPI download count. Primary pypistats.org
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    verifiers, GitHub. It gives stars, licence and release data. Primary github.com
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    verifiers downloads, pypistats. It gives the monthly PyPI download count. Primary pypistats.org
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    ControlArena repository. It describes the AI control library from UK AISI and Redwood. Primary github.com
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    pyrit downloads, pypistats. It gives the monthly PyPI download count. Primary pypistats.org
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