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Langfuse

Free tier

Open-source AI engineering platform to debug, monitor, and improve LLM applications and agents

Free tier available·Technical·API available·Open source

Key strengths

Open source (MIT licensed)Self-hostable at scaleLLM observability and tracingPrompt managementLLM-as-a-judge and human evaluation100+ integrations / OTel nativeEnterprise scale (90B+ observations/month)No framework lock-in
Free tier + paid plans · from $29 USD/mo
Founded 2023
Self-hostable

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Recent changes

  • Plans updated: Hobby (free): 50k units/month, 30 days data access, 2 users. Core: $29/month, 100k units/month included, 90 days data access, unlimited users. Pro: $199/month, 100k units/month included, 3 years data access, high rate limits, SOC2 & ISO27001. Enterprise: $2,499/month. Additional usage: $8/100k units.
  • Starting price: $0/mo → $29/mo
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Technical Use Cases

Langfuse is purpose-built for AI/ML engineers and teams working on LLM applications and agents. Common technical use cases include:

  • Agent tracing & debugging — Capture multi-step agent execution traces (tool calls, LLM calls, sub-agents) to diagnose failures and latency bottlenecks across frameworks like CrewAI, OpenAI Agents SDK, AutoGen, and LangChain
  • LLM observability in production — Monitor token usage, latency, cost, and error rates across model providers (OpenAI, Anthropic, Bedrock, Gemini, etc.) with OTel-native instrumentation
  • Prompt engineering & versioning — Manage prompt templates with version control, run A/B experiments, and link prompt versions directly to production trace data
  • Automated evaluation pipelines — Implement LLM-as-a-judge scoring at scale; integrate with Ragas, Promptfoo, or custom scoring logic via the API
  • Human annotation workflows — Route traces to human reviewers for structured labeling and quality assessment
  • RAG pipeline monitoring — Trace retrieval and generation steps in RAG systems; integrates with LlamaIndex, RAGflow, and LiteLLM
  • Self-hosted enterprise deployments — Run Langfuse on-premises with ClickHouse for high-throughput analytics; SOC2 & ISO27001 compliance available on Pro and Enterprise plans
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