Open source LLM engineering platform: traces LLM and agent calls, manages prompts, runs evaluations and tracks cost and latency. Self-host or use the cloud; acquired by ClickHouse in 2026.
Pricing and hosting
- Pricing
- Free plan
- Free plan
- 50k units/mo, 30 days data access, 2 users
- Open source
- Yes (MIT)
- Self-hosted
- Yes
- Launched
- 2023
- Status
- Active
- Website
- langfuse.com
Plans and prices change; check the tool's own site before you decide.
What it does
LLM and AI observability checklist
9 of 10 confirmed in Langfuse's own documentation. The same checklist is used for every tool in LLM observability.
- LLM call tracing Yes
- Agent and multi-step traces Yes
- Token and cost tracking Yes
- Prompt management Yes
- Evaluations Yes
- Datasets and experiments Yes
- User feedback Yes
- OpenTelemetry support Yes
- Playground Yes
- Alerts Not confirmed
'Spend alerts' are for Langfuse billing; no alerts on app cost/latency/quality found (dashboards and prompt webhooks only).
Checked against: github.com, langfuse.com, langfuse.com (2)
Alternatives to Langfuse
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Arize Phoenix Source-available LLM tracing and evaluation tool built on OpenTelemetry and OpenInference; run it locally, in a notebook or on your servers to inspect traces and score outputs. -
Braintrust Evaluation and observability platform for AI products: logs production traces, runs evals and scorers, and offers a prompt playground and datasets. -
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Galileo AI evaluation and observability platform with tracing, evaluation metrics and real-time guardrails for agents; hosted, VPC or on-prem. -
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HoneyHive Observability and evaluation platform for AI agents: OpenTelemetry-based tracing, automated and human evals, prompt versioning and production monitoring. -
Laminar Open source observability for AI agents: OpenTelemetry-based tracing, evaluations and analysis of agent runs, self-hostable or cloud. -
LangSmith LangChain's platform for tracing, evaluating and monitoring LLM apps and agents, usable with or without LangChain; also hosts agent deployments. -
LangWatch Open source LLMOps platform: traces LLM and agent runs, runs evaluations and agent simulations, and helps optimize prompts; cloud or self-managed.