API & Data Platform

Langfuse is designed to be open, extensible and flexible (see why langfuse?). People using Langfuse are building all kinds of workflows and customizations on top of it. This is powered by our open data platform.

Example use cases:

Billing based on LLM costs tracked in Langfuse
Reporting of online evaluations in external dashboards
Fine-tuning based on raw exports of traces
Correlation of LLM Evals with observed user behavior in Data Warehouse

Start here

Choose the data access path based on what you want to build:

Goal	Recommended path
Query aggregate cost, usage, latency, volume, or score metrics	Metrics API v2
Retrieve row-level spans, generations, or events	Observations API v2
Use the API from Python or JS/TS	Query via SDKs
Export large volumes on a schedule	Blob Storage Export
Download a filtered one-off export	Export from UI
Manage prompts, datasets, projects, and other resources	Public API

Features

MCP Server

Public API

Query via SDKs

Observations API

Metrics API

Export from UI

Export to Blob Storage

Export to PostHog

Export to Mixpanel

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