langfuse.com · Observability
Open source LLM engineering platform (MIT core) for tracing, prompt management, datasets and evals, free to self host. Owned by ClickHouse since January 2026.
Langfuse is one of 10 observability tools on TrueIQ. See all observability tools or how we check facts.
// guides
What is answer completeness in RAG evaluation? The share of key facts from a reference answer that a response covers, and how Azure, Bedrock and Ragas score it.
How to use LangSmith with LangGraph: set four environment variables, read node traces and threads, then score your graph and single nodes on a dataset.
Is LangSmith API free? Yes: API keys and the REST API cost nothing, and the Developer plan covers 5,000 traces a month. See key types, limits and overage costs.
Is Langfuse free for commercial use? Yes: the MIT core can be self hosted in paid products at no cost. See what needs a license key and when the cloud bills.
Datadog LLM Observability vs Langfuse: how each bills (LLM spans vs units), retention, self hosting, evals and setup, with worked cost examples for 2026.
The Artificial Hivemind paper explained: why AI models give the same answers, what Infinity-Chat and NoveltyBench measure, and how to test output diversity yourself.
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