langfuse-js

[!IMPORTANT] This SDK is deprecated. The Langfuse TypeScript SDK was completely rewritten and released as v4 in August 2025. Please refer to the TypeScript SDK documentation for migration instructions.

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

Packages

Package	NPM	Environments
langfuse		Node >= 18, Web, Edge
langfuse-node		Node < 18
langfuse-langchain		Node >= 20, Web, Edge
langfuse-vercel (beta)		Node >= 20, Web, Edge

Documentation

• Docs: https://langfuse.com/docs/sdk/typescript
• Reference: https://js.reference.langfuse.com

License

MIT

Credits

Thanks to the PostHog team for the awesome work on posthog-js-lite. This project is based on it as it was the best starting point to build a modular SDK repo to support various environments.