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Langfuse

Freemium
llmopsobservabilityopen sourcedeveloper toolsprompt engineeringllm evaluationtracingairag

An open-source LLM engineering platform providing comprehensive tools for tracing, debugging, evaluating, and monitoring LLM applications to help teams build and ship reliable AI products from development to production.


Langfuse is an open-source platform designed for developers and teams building applications on top of large language models (LLMs). It helps them debug, monitor, and improve their LLM-powered features through detailed tracing, evaluation frameworks, prompt management, and cost analytics. Unlike some proprietary-only solutions, its open-source nature offers significant flexibility, including self-hosting options and a transparent development model driven by community contributions. The platform unifies the entire LLM development lifecycle, from initial experimentation with prompts to production monitoring and user feedback analysis. It primarily serves ML engineers, data scientists, and full-stack developers who require robust, specialized tooling to build and maintain reliable and scalable AI products.

Pros

  • Open-source core provides flexibility, transparency, and self-hosting capabilities.
  • Combines tracing, evaluations, prompt management, and cost analytics in a single unified platform.
  • Offers granular, nested traces for complex RAG pipelines and agentic workflows, simplifying debugging.
  • Framework-agnostic with SDKs for Python and TypeScript/JavaScript, integrating with popular LLM libraries.
  • Strong, active community and comprehensive documentation for support and troubleshooting.

Cons

  • Self-hosting requires dedicated infrastructure and maintenance overhead, which may challenge smaller teams.
  • The extensive feature set can present a steep learning curve for new users.
  • Usage-based pricing for paid cloud tiers can lead to unpredictable costs at high volumes.
  • The UI is primarily developer-focused and may be less intuitive for non-technical users like product managers.

Key features

  • Detailed LLM Tracing
  • Prompt Management & Versioning
  • Model Evaluation & Testing Datasets
  • Cost Analytics and Monitoring
  • Open-Source Core and Self-Hosting
  • SDKs for Python & JS/TS
  • User Feedback Collection API
  • Role-Based Access Control (RBAC)

Integrations

LangChainLlamaIndexOpenAIAnthropicCohereMistral AIGoogle Vertex AILiteLLMHaystackNext.js

Target audience

Developers, LLM engineers, data scientists, and product teams building, monitoring, and iterating on applications powered by large language models.


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Founded

2023

Headquarters

Berlin, Germany

Pricing Tiers

Cloud Hobby

Includes 50,000 observations/month, 1 project, 3 team members, and 7-day data retention. Ideal for personal projects and initial exploration.

Free

Cloud Pro

Starts with 100,000 observations/month, then usage-based pricing. Includes unlimited projects, unlimited members, 30-day data retention, and Role-Based Access Control (RBAC).

$50/mo

Enterprise

For large-scale deployments, available as self-hosted or on a dedicated cloud. Includes unlimited observations, members, and projects, plus features like SSO, custom data retention, and dedicated support.

Custom


Frequently Asked Questions


Top Alternatives to Langfuse

LangSmith

A strong choice from the creators of LangChain, offering exceptional, seamless integration if you are already heavily invested in that specific framework.

Weights & Biases

A comprehensive MLOps platform supporting LLM experimentation, often preferred by teams already using it for traditional ML model training and tracking.

Arize AI

A broader machine learning observability platform that has extended into LLMs, making it a good fit for teams wanting a single solution to monitor both traditional ML and LLM applications.

Phoenix (by Arize)

An open-source alternative focused on LLM evaluation and observability in a notebook environment, appealing to users who prioritize local, code-first analysis.

Ready to get started?

Join thousands of users and see how Langfuse can transform your workflow today.

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