Langfuse

LLM tracing & cost monitoring

Open source, self-hostable, GDPR-native. Every LLM call is traced: input, output, duration, token cost per model. Cost dashboard per agent, per tenant, per feature.

vs. LangSmith: Langfuse for data sovereignty (self-host on Scaleway). LangSmith if you want to stay 100% cloud Langchain.