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Repository

langfuse-js

🪢 Langfuse JS/TS SDKs - Instrument your LLM app and get detailed tracing/observability. Works with any LLM or framework

Langfuse
Repository
Package
NPM
@langfuse/client
Langfuse API client for universal JavaScript environments
@langfuse/browser
Langfuse browser SDK for public-key score ingestion
@langfuse/tracing
Langfuse instrumentation methods based on OpenTelemetry

Specs

  • PackageNPM
  • @langfuse/clientLangfuse API client for universal JavaScript environments
  • @langfuse/browserLangfuse browser SDK for public-key score ingestion
  • @langfuse/tracingLangfuse instrumentation methods based on OpenTelemetry
  • @langfuse/otelLangfuse OpenTelemetry export helpers
  • @langfuse/openaiLangfuse integration for OpenAI SDK
  • @langfuse/langchainLangfuse integration for LangChain
  • @langfuse/vercel-ai-sdkLangfuse integration for AI SDK v7

README

hero-b

langfuse-js

MIT License
CI test status
GitHub Repo stars
Discord
YC W23

Modular mono repo for the Langfuse JS/TS client libraries.

Packages

[!IMPORTANT]
The SDK was rewritten in v5 and released in March 2026. Refer to the v5 migration guide for instructions on updating your code.

The unscoped npm packages langfuse, langfuse-core, langfuse-node, and langfuse-langchain belong to the legacy v3 SDK. For new integrations use the @langfuse/* scoped packages below — start with @langfuse/tracing + @langfuse/otel for tracing.

Package NPM Description Environments
@langfuse/client NPM Langfuse API client for universal JavaScript environments Universal JS
@langfuse/browser NPM Langfuse browser SDK for public-key score ingestion Browser
@langfuse/tracing NPM Langfuse instrumentation methods based on OpenTelemetry Node.js 20+
@langfuse/otel NPM Langfuse OpenTelemetry export helpers Node.js 20+
@langfuse/openai NPM Langfuse integration for OpenAI SDK Universal JS
@langfuse/langchain NPM Langfuse integration for LangChain Universal JS
@langfuse/vercel-ai-sdk NPM Langfuse integration for AI SDK v7 Universal JS

Documentation

Development

This is a monorepo managed with pnpm. See CONTRIBUTING.md for detailed development instructions.

Quick start:

pnpm install    # Install dependencies
pnpm build      # Build all packages
pnpm test       # Run tests
pnpm ci         # Run full CI suite

License

MIT