Langfuse

Langfuse is an open source LLM engineering platform that helps teams debug, evaluate, monitor, and manage prompts for production AI applications. It is a popular self-hostable alternative to LangSmith and Helicone for teams that want full control of their LLM telemetry.

Langfuse provides detailed tracing of LLM calls, OpenTelemetry-native instrumentation, automatic prompt versioning, evaluation datasets, and a managed playground for prompt engineering. It integrates with LangChain, OpenAI, LiteLLM, Anthropic, and the broader OpenTelemetry ecosystem.

Released under an MIT-style license and built with TypeScript and Python, Langfuse is widely used by startups and enterprises that need an open, vendor-neutral observability stack for LLM-powered products.