Langfuse / langfuse.com
Open source LLM observability and evaluation platform for tracing, debugging, and monitoring AI applications in development and production.
Free plan
Yes
API access
Yes
Open source
Yes
Platforms
3
Langfuse is an open source observability platform specifically designed for LLM-powered applications. As AI applications move from prototype to production, understanding why they behave as they do becomes critical, and traditional application monitoring tools are not equipped to handle the specific challenges of language model applications.
The core capability is tracing. Langfuse wraps LLM API calls and captures the complete input-output-metadata for each request, storing it in a structured format that allows debugging, analysis, and optimisation. When an AI application produces an unexpected or poor-quality response, traces allow developers to see exactly what prompt was sent, which model was used, what the response was, how much it cost, and how long it took.
Evaluation features allow scoring LLM outputs either manually (human annotation), through LLM-based evaluation (asking a judge model to rate responses), or through custom scoring functions. Systematically evaluating output quality across many samples is essential for AI application quality assurance that goes beyond testing individual examples.
Datasets for testing allow capturing representative inputs, running the application against them, and comparing results across different prompt versions or model changes. This enables regression testing for AI applications where quality can change subtly when prompts or models are updated.
Langfuse runs as ml platform software built around text and code workflows. Users typically start with a prompt, upload, or connected data source, and the underlying model handles the heavy lifting before returning a result you can refine or export. It's available on web, python sdk, and typescript sdk, with API access for teams that want to embed it into their own products.
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The capabilities that matter most for teams evaluating Langfuse.
Captures complete input-output-metadata for every LLM API call for debugging, analysis, and production monitoring.
Systematic quality assessment of LLM outputs through manual annotation, LLM-based judging, or custom scoring functions.
Capture representative test cases and run regression testing when prompts or models change.
Free self-hosted (open source). Hobby cloud plan free. Pro cloud $59/month. Team $399/month. Enterprise custom pricing.
Model
Open Source
Starting price
$59/mo
Free trial
No
LangSmith from LangChain is the primary alternative with tighter LangChain integration. Helicone is a simpler observability layer focused on cost monitoring. Weights & Biases Weave provides LLM observability alongside broader ML experiment tracking.
A side-by-side look at the closest alternative in this category.
Key facts about model providers, platforms, and team support.
Model Provider
Agnostic
Platforms
Web, Python SDK, TypeScript SDK
Deployment
Open Source, SaaS, Self-hosted
Integrations
LangChain, LlamaIndex, OpenAI, Anthropic, GitHub Actions, Vercel AI SDK
Team Collaboration
No
Launch Year
2023
Compliance signals and data-handling notes as reported by the vendor.
Self-hosted: complete data control. Cloud: review Langfuse's data handling policy. Enterprise includes data processing agreements.
Self-hosted Langfuse keeps all trace data within your infrastructure. Cloud version processes trace data on Langfuse's servers. Review privacy policy for applications with sensitive user data.
Editorial Verdict
Langfuse is essential infrastructure for development teams building serious LLM applications in production. Self-hosting makes it accessible even for teams with data privacy requirements.
Last verified July 24, 2026.
The open source nature allows self-hosting for complete data control, which is important for teams whose LLM applications process sensitive data. The cloud version is available for teams that prefer managed infrastructure.
For teams building serious LLM applications in production, Langfuse or a similar observability tool is essential infrastructure. LangSmith from LangChain is the primary competitor.
Free self-hosted (open source). Hobby cloud plan free. Pro cloud $59/month. Team $399/month. Enterprise custom pricing.
Free plan with 100,000 requests/month. Pro $20/month with more requests and features. Teams and Enterprise custom pricing. Open source self-hosted option available.
Self-hosted: complete data control. Cloud: review Langfuse's data handling policy. Enterprise includes data processing agreements.
Open source self-hosted provides complete data control. Cloud proxy: review Helicone's data handling policy. Production AI traffic routed through Helicone's infrastructure.
Self-hosted Langfuse keeps all trace data within your infrastructure. Cloud version processes trace data on Langfuse's servers. Review privacy policy for applications with sensitive user data.
Cloud version routes all AI API traffic through Helicone's proxy. Review privacy implications for sensitive production data. Self-hosted option provides complete data control.
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