Langfuse
by Langfuse
Open-source LLM observability. Traces, evals, prompt management, all self-hostable.
OSS
Langfuse
Added 17 May 2026
Overview
Langfuse is the most popular open-source observability platform for LLM apps. Traces, evals, prompt management, datasets, and cost tracking all in one place. Self-hostable for compliance-sensitive teams, hosted SaaS for everyone else. Pairs with most major frameworks via official integrations.
Best for
Best for
Teams running LLM apps in production who need real observability
Use cases
- Trace and debug every LLM call across a production app
- Manage prompts as versioned, deployable artefacts
- Run evals against real production data
- Track cost and latency per workflow
Notes
Why it matters
You cannot fix what you cannot see. Langfuse is the cleanest open-source answer for seeing what your LLM app is actually doing in production.
How teams use it in production
Wire Langfuse on day one, not after the first incident. Set cost alerts. Add evals as soon as the first user-facing flow stabilises.
What to watch
The split between Langfuse, Helicone, Arize, and LangSmith is the live race in LLM observability. Self-hosting capability is the obvious differentiator.
Pros
- Open source and self-hostable, no lock-in
- Strong integrations with most major frameworks
- Prompt management is a separately useful surface
- Active development and large community
Cons
- Self-hosting adds infra scope
- Some advanced eval features still hosted-only
- UI density can intimidate first-time users
Pairs with
Other entries in the index that connect to this one. Click through to see the chain.