What Langfuse does
Langfuse is an open-source LLM engineering platform that helps teams develop, monitor, evaluate, and debug AI applications. It is purpose-built for LLM-based software, natively understanding concepts like token usage, model parameters, prompt and completion pairs, and evaluation scores.
Key capabilities
Langfuse provides observability and tracing by instrumenting applications and ingesting traces that capture LLM calls along with retrieval, embedding, and agent actions. Its prompt management lets teams centrally version, manage, and iterate on prompts with strong caching to avoid added latency. It supports evaluations, including managed LLM-as-a-judge scoring on production or development traces, plus datasets and experiments for building test sets and benchmarks. It integrates with OpenTelemetry, LangChain, the OpenAI SDK, LiteLLM, and other frameworks.
Who it's for
Langfuse serves developers and engineering teams building LLM applications and AI agents who need visibility, evaluation, and iteration tooling. It can be self-hosted or used as a managed service with a free tier, and is used by thousands of companies. The platform is open source and the company is part of Y Combinator's W23 batch, headquartered in Germany.