Introduction

Langfuse is an open source product analytics suite for LLM apps.

Features

1. Integrations: Data collection via SDKs
   • Tracing LLM chains by collecting specific data such as prompts, outputs, and configurations
   • Measure quality of outputs via Scores
     • Manually in Langfuse UI (human-in-the-loop)
     • User feedback, explicit or implicit, optionally directly from the browser via Web SDK
     • Model-based evaluation
     • Custom via SDK/API
2. Nested traces
   • Find the root cause of issues
   • Segment traces based on user feedback and other metrics
3. Analytics
   • User-level reporting: costs, usage, feedback/quality
   • Usage/cost

Why Langfuse?

• Open source (MIT license)

• Run Langfuse self-hosted, locally, or use Langfuse cloud

• Model agnostic

• Integration

  • Fully async SDKs for:
    • JS/TS (Node, Edge)
    • Python
  • Langchain integration (full integration in 5 minutes)
  • Public API
  • OpenAI SDK (drop-in replacement, change only the import)
  • JS/TS Web SDK to create scores from the client-side
  • Incrementally adoptable, start with a single LLM call, expand to full tracing of complex chains/agents

• Use GET API to build downstream use cases

What's next?

Get in touch

Langfuse is being actively developed in open source together with the community. Join our Discord! Provide feedback, report bugs, or request features via GitHub issues.

If you want to chat about your use case, reach out to us via email (contact@langfuse.com) or schedule a demo.