Langfuse

Langfuse is an open-source platform for building and operating LLM-powered applications. It helps teams trace model behavior, evaluate quality, manage prompts, and track metrics so you can debug issues and improve performance over time.

Key capabilities

• LLM tracing and monitoring to collect and analyze runtime data
• Prompt versioning and collaborative prompt management
• Model quality and performance evaluation
• Manual annotation with custom labels and comments
• Dataset creation and management for training and testing
• Metrics and statistics for performance analysis
• Sandbox for quick testing and experimentation

How to get started

Langfuse is available as an open-source web application. Typical setup includes:

• Create an account and a new project
• Install an SDK (for example, Python or JavaScript)
• Integrate the SDK into your app to trace and manage LLM calls
• Configure settings and start using monitoring, prompts, and evaluation tools

Langfuse can be used for free without limits and can also be self-hosted. It supports English and integrates with common LLM tooling, including LlamaIndex, Langchain, and the OpenAI SDK.