Langfuse

The most-used open-source LLM observability tool.

Visit site GitHub
Open source Self-hostable Featured freemium
LicenseMIT
Starting priceSelf-host free; cloud tier
Model supportmulti
Languagespython, typescript
GitHub stars29.8k
Last activity2026-06-25
VerifiedThu Jun 25 2026 00:00:00 GMT+0000 (Coordinated Universal Time)
Verified byseed

An open-source platform for tracing, prompt management, and evaluation that you can self-host to keep traces private.

Strengths

  • Open source and self-hostable
  • Framework-agnostic via OpenTelemetry

Tradeoffs

  • Self-hosting ClickHouse is operational work
  • Eval features trail dedicated eval tools

Knowledge

Curated, novelty-scored insights for Langfuse, drawn from verified sources. The pipeline ingests video transcripts and extracts only the claims that add new signal.

Langfuse is the most-used open-source LLM observability tool; self-hosting keeps sensitive traces off vendor servers.
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For pure regression testing rather than tracing, pair Langfuse with a dedicated eval tool; tracing alone will not catch quality drift.
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