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Rank #5 of 8 in LLM Evals & Observability

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Langfuse

Open SourceYC W23

Langfuse GmbH

34.6k10.4k/yrnpm 1.4M/wkpypi 5M/wk +438npm/wk -406.5kpypi/wk +207.1k

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Install

pippip install langfuse
npmnpm install @langfuse/tracing @langfuse/otel @opentelemetry/sdk-node

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Langfuse homepage screenshot
homepage · captured Sep 2026 · view live ↗
Langfuse docs screenshot
docs · captured Sep 2026 · view live ↗

Verified integrations

Connections to other tracked products — hover a chip for the verbatim evidence quote behind it.

By theme — the product's score on each story themeBy theme

Agenticness — how well agents can access and operate the productAgenticnessevidence →

How well agents can access and operate the product

33.0/100

Alerting dashboards — stories about alerting dashboards in this arenaAlerting dashboardsevidence →

Stories about alerting dashboards in this arena

58.0/100

Automation depth — how much of the product can run unattendedAutomation depthevidence →

How much of the product can run unattended

17.3/100

Cost monitoring — stories about cost monitoring in this arenaCost monitoringevidence →

Stories about cost monitoring in this arena

82.0/100

Data access export — stories about data access export in this arenaData access exportevidence →

Stories about data access export in this arena

80.0/100

Evals datasets — measuring quality — datasets, eval runs, regression trackingEvals datasetsevidence →

Measuring quality — datasets, eval runs, regression tracking

72.8/100

Openness — open source, data portability, and self-hosting storiesOpennessevidence →

Open source, data portability, and self-hosting stories

61.0/100

Privacy posture — data-handling and privacy storiesPrivacy postureevidence →

Data-handling and privacy stories

13.3/100

Prompt management — stories about prompt management in this arenaPrompt managementevidence →

Stories about prompt management in this arena

76.0/100

Tracing instrumentation — instrumenting code and tracing requests end to endTracing instrumentationevidence →

Instrumenting code and tracing requests end to end

59.9/100

Story verdicts — every judged story with its evidenceStory verdicts

What’s free: 2 free · 0 paid · 0 enterprise · 38 not stated in evidence

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Sorted by importance (agentic first) (high → low) · 52/52 stories · click a row’s chevron for the rationale and evidence

Connect an agent via an official MCP server G

Agent access

ai-native userAgenticness — how well agents can access and operate the productAgenticness3full7/10T

Drive the product through a documented public API G

Agent access

ai-native userAgenticness — how well agents can access and operate the productAgenticness3partial6/10T

Delegate tasks to a built-in AI assistant inside the product G

Agentic features

ai-native userAgenticness — how well agents can access and operate the productAgenticness3none0/10

Plug MCP servers into this product so it can use their tools G

Agent access

ai-native userAgenticness — how well agents can access and operate the productAgenticness3n/a0/10

Point an agent at llms.txt or agent-oriented docs G

Agent access

ai-native userAgenticness — how well agents can access and operate the productAgenticness2full9/10T

Build against official SDKs G

Agent access

ai-native userAgenticness — how well agents can access and operate the productAgenticness2full8/10T

Use an official CLI G

Agent access

ai-native userAgenticness — how well agents can access and operate the productAgenticness2full7/10C

Operate the product with natural-language commands G

Agentic features

ai-native userAgenticness — how well agents can access and operate the productAgenticness2partial6/10T

Run the product headlessly / in CI for automation G

Agent access

ai-native userAgenticness — how well agents can access and operate the productAgenticness2partialfree6/10C

Subscribe to events via webhooks G

Agent access

ai-native userAgenticness — how well agents can access and operate the productAgenticness2partial5/10C

Get AI-generated insights and suggestions from my data inside the product G

Agentic features

ai-native userAgenticness — how well agents can access and operate the productAgenticness2partial4/10C

Set up automations that run autonomously in the background G

Agentic features

ai-native userAgenticness — how well agents can access and operate the productAgenticness2partial4/10C

Download a machine-readable API spec (OpenAPI or equivalent) G

Api quality

ai-native userAgenticness — how well agents can access and operate the productAgenticness2none0/10

Explore an interactive API reference with runnable examples G

Api quality

ai-native userAgenticness — how well agents can access and operate the productAgenticness2none0/10

Rely on versioned APIs with a documented deprecation policy G

Api quality

ai-native userAgenticness — how well agents can access and operate the productAgenticness2none0/10

Issue scoped/least-privilege API credentials for an agent G

Agent access

ai-native userAgenticness — how well agents can access and operate the productAgenticness2noneuntestednone yet

Test against a sandbox environment without touching production data G

Api quality

ai-native userAgenticness — how well agents can access and operate the productAgenticness1partialfree4/10C

Capture traces of my LLM calls with inputs, outputs, latency, and token usage C

Trace capture

developerTracing instrumentation — instrumenting code and tracing requests end to endTracing instrumentation3full9/10X

See cost and token usage per request, model, and time period in dashboards C

Cost tracking

developerCost monitoring — stories about cost monitoring in this arenaCost monitoring3full9/10X

Self-host the core product G

ai-native userOpenness — open source, data portability, and self-hosting storiesOpenness3full9/10T

Compare eval runs side by side to catch regressions between prompt or model versions C

Offline evals

ml engineerEvals datasets — measuring quality — datasets, eval runs, regression trackingEvals datasets3full8/10C

Curate datasets from production traces and run offline evaluations against them C

Offline evals

ml engineerEvals datasets — measuring quality — datasets, eval runs, regression trackingEvals datasets3full8/10C

Score outputs with configurable LLM-as-a-judge evaluators C

Offline evals

ml engineerEvals datasets — measuring quality — datasets, eval runs, regression trackingEvals datasets3full8/10C

Send and receive traces over OpenTelemetry (OTLP) instead of a proprietary format C

Trace capture

developerTracing instrumentation — instrumenting code and tracing requests end to endTracing instrumentation3full8/10C

Version prompts and deploy changes to production without shipping code C

Prompt workflow

developerPrompt management — stories about prompt management in this arenaPrompt management3full8/10X

Export all of my data in open formats and leave G

ai-native userOpenness — open source, data portability, and self-hosting storiesOpenness3partial6/10X

Have an agent query my traces, metrics, and eval results through an API or MCP server to debug my app C

Ai observability

ai-native userTracing instrumentation — instrumenting code and tracing requests end to endTracing instrumentation3partial6/10T

Define rules that trigger actions automatically on events G

ai-native userAutomation depth — how much of the product can run unattendedAutomation depth3partial4/10C

Prevent my data from being used to train AI models G

ai-native userPrivacy posture — data-handling and privacy storiesPrivacy posture3partial3/10C

Build custom dashboards over latency, error, cost, and eval-score metrics C

Monitoring

ml engineerAlerting dashboards — stories about alerting dashboards in this arenaAlerting dashboards2full8/10C

Bulk-export traces and datasets to blob storage or my data warehouse C

Data export

developerData access export — stories about data access export in this arenaData access export2full8/10X

Instrument apps in both Python and JS/TS with officially supported SDKs G

Sdk coverage

developerTracing instrumentation — instrumenting code and tracing requests end to endTracing instrumentation2full8/10X

Read the product's source under an open license G

ai-native userOpenness — open source, data portability, and self-hosting storiesOpenness2full8/10T

Route outputs to human annotation queues for review and labeling C

Human review

ml engineerEvals datasets — measuring quality — datasets, eval runs, regression trackingEvals datasets2full8/10C

Trace multi-step agent runs as nested spans grouped into sessions or threads C

Trace capture

developerTracing instrumentation — instrumenting code and tracing requests end to endTracing instrumentation2full8/10X

Attribute cost and usage to users, sessions, and features via custom metadata C

Cost tracking

developerCost monitoring — stories about cost monitoring in this arenaCost monitoring2full7/10C

Have an agent create a dataset, trigger an eval run programmatically, and read back the results C

Ai eval ops

ai-native userEvals datasets — measuring quality — datasets, eval runs, regression trackingEvals datasets2partial7/10C

Instrument my app through existing integrations for frameworks like LangChain, the OpenAI SDK, or the Vercel AI SDK C

Trace capture

developerTracing instrumentation — instrumenting code and tracing requests end to endTracing instrumentation2full7/10X

Iterate on prompts in a playground against real models and variables C

Prompt workflow

developerPrompt management — stories about prompt management in this arenaPrompt management2full7/10X

Run evals in CI and gate deployments on their results C

Offline evals

developerEvals datasets — measuring quality — datasets, eval runs, regression trackingEvals datasets2full7/10C

Run evaluators continuously on live production traffic, not just offline datasets C

Online evals

ml engineerEvals datasets — measuring quality — datasets, eval runs, regression trackingEvals datasets2full7/10C

Write custom code-based scorers and metrics for my evaluations C

Offline evals

ml engineerEvals datasets — measuring quality — datasets, eval runs, regression trackingEvals datasets2full7/10C

Do everything through the API that I can do in the UI G

ai-native userOpenness — open source, data portability, and self-hosting storiesOpenness2partial6/10T

Set alerts on error rates, cost spikes, or eval-score drops and get notified in Slack, PagerDuty, or email C

Monitoring

developerAlerting dashboards — stories about alerting dashboards in this arenaAlerting dashboards2partial6/10C

Choose where my data is stored (region/residency) G

ai-native userPrivacy posture — data-handling and privacy storiesPrivacy posture2disputed5/10D

Perform bulk operations across many items at once G

ai-native userAutomation depth — how much of the product can run unattendedAutomation depth2disputed5/10D

Control data retention and deletion G

ai-native userPrivacy posture — data-handling and privacy storiesPrivacy posture2partial3/10X

Mask or redact sensitive data before it is stored in traces C

Data controls

developerTracing instrumentation — instrumenting code and tracing requests end to endTracing instrumentation2noneuntestednone yet

Opt out of telemetry and usage tracking G

ai-native userPrivacy posture — data-handling and privacy storiesPrivacy posture2noneuntestednone yet

Schedule recurring jobs or workflows G

ai-native userAutomation depth — how much of the product can run unattendedAutomation depth2noneuntestednone yet

Version, review, and roll back my automations G

ai-native userAutomation depth — how much of the product can run unattendedAutomation depth1partial6/10C

Capture multimodal payloads (images, audio, files) inside my traces C

Trace capture

developerTracing instrumentation — instrumenting code and tracing requests end to endTracing instrumentation1noneuntestednone yet

Opportunities — the stories that would move this product's scores, from its own judged verdictsOpportunitiestop 8 of 25 stories with headroom

What would move Langfuse’s scores — derived from its own judged verdicts, biggest headroom first. Each line quotes what the judge found missing; shipping it (or evidencing it publicly) is the fix.

  1. Agenticness — how well agents can access and operate the productDelegate tasks to a built-in AI assistant inside the product

    nonemoves Built-in AIimpact 45

    Langfuse's evidence covers observability, prompt management, evaluation, MCP server connectivity, and self-hosting, but nothing describes a built-in AI assistant within the product itself that users can delegate tasks to; the MCP/docs-mcp features are for external coding agents integrating with Langfuse, not an assistant embedded in the Langfuse UI.

  2. Agenticness — how well agents can access and operate the productIssue scoped/least-privilege API credentials for an agent

    nonemoves agent-readyimpact 30

    The evidence pack documents Langfuse's tracing, prompt management, evaluation, and API/export features, but contains no mention of API key scoping, role-based permissions, or least-privilege credential issuance for agents.

  3. Agenticness — how well agents can access and operate the productExplore an interactive API reference with runnable examples

    nonemoves API qualityimpact 30

    Missing: any documentation or screenshot of an interactive API explorer, runnable code snippets in an API reference UI, or a working OpenAPI/Swagger spec.

  4. Agenticness — how well agents can access and operate the productDownload a machine-readable API spec (OpenAPI or equivalent)

    nonemoves API qualityimpact 30

    While Langfuse's docs reference an API, SDKs, and a Metrics API v2, a direct probe for a machine-readable spec (openapi.json, swagger.json, etc.) returned 404 on all candidate paths, and no evidence pack item links to a downloadable OpenAPI/Swagger file.

  5. Agenticness — how well agents can access and operate the productRely on versioned APIs with a documented deprecation policy

    nonemoves API qualityimpact 30

    Evidence shows an API exists (e.g., 'Metrics API v2') but there is no documentation of a versioning scheme or deprecation policy; the OpenAPI spec probe even returned 404s across candidate paths, suggesting no discoverable API spec/versioning docs.

  6. Privacy posture — data-handling and privacy storiesPrevent my data from being used to train AI models

    partialq3/10moves PA Scoreimpact 21

    Missing: explicit data-usage/training policy, DPA or privacy documentation addressing model training, and independent confirmation of this stance for Langfuse Cloud users.

  7. Automation depth — how much of the product can run unattendedSchedule recurring jobs or workflows

    nonemoves PA Scoreimpact 20

    Langfuse is an observability/evaluation platform for LLM apps; while it has scheduled exports and alerts, there is no evidence of user-defined recurring job/workflow scheduling (e.g., cron-like automation of arbitrary tasks) as an ai-native automation capability.

  8. Tracing instrumentation — instrumenting code and tracing requests end to endMask or redact sensitive data before it is stored in traces

    nonemoves PA Scoreimpact 20

    No evidence in the pack mentions masking, redaction, or PII scrubbing before trace storage; the docs cover tracing, prompt management, evaluation, and deployment but not data masking capabilities.

Showing the top 8 of 25 — every none/partial verdict in the story verdicts table is headroom.

Think a verdict is wrong? Every verdicts-table row has a Flag link — see the methodology.

Coverage map — which docs area, API section, or community source covers which judged storiesCoverage map6 surfaces · 42 covered stories

Where the cited evidence behind each covered verdict came from — the same citations the verdicts table shows, no extra judging.

docs38 stories

Claims vs evidence — vendor claims reconciled against independent verdictsClaims vs evidence

14 of 26 testable claims verified · 0 contradictedintegrity 54/100

36 distinct capability claims found in Langfuse’s own claimed-docs/GitHub materials, reconciled against our judge’s independent verdicts.

14

Verified

12

Unverified

0

Contradicted

14

Undersold

Verified (24)
Unverified (20)
Undersold (14)
Claims outside our story set (2)

Real capability claims found in Langfuse’s own materials, but no story in this arena’s taxonomy covers them yet — that’s feedback on the taxonomy, not a mark against the product.

  • AI coding agents like Cursor can automatically integrate Langfuse tracing into a codebase

    source ↗
  • End-user feedback can be collected via User Feedback feature

    source ↗
Suggest a story for these →

Business model

open-sourcefree-tiersubscription-flatusage-basedenterprise-custom

MIT-licensed core you can self-host free; Langfuse Cloud has a free Hobby tier, then flat monthly Core/Pro plans with usage-based unit ingestion, and custom enterprise plans.

pricing ↗

Score trend

How this product’s scores have moved as evidence and verdicts are re-derived — a point per change, not per day.

PA Score35 (Sep 4 '26)34 (Sep 4 '26)
Agent-ready49 (Sep 4 '26)52 (Sep 4 '26)

Flag

⚑ Flag a verdict

Think a verdict is wrong? Opens a prefilled GitHub issue — or use the ⚑ next to any verdict above.

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For agents

Data

Agent surface uptime llms.txt 100% (30d, checked every 6h since Sep 8 '26)