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@langfuse/core

v5.11.0

Published

Core functions and utilities for Langfuse packages

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Links

Git

Maintainers

bezbacbezbacmdeichmannmdeichmannmarliessophiemarliessophiehassiebhassiebmarcklingenmarcklingenwochingewochinge

Keywords

Readme

GitHub Banner

@langfuse/core

Langfuse is the open-source LLM engineering platform: tracing & evaluation for AI and agent applications, prompt management, datasets & experiments, and evaluation (scores). This is the shared core package of the Langfuse JS SDK: the generated REST API client (LangfuseAPIClient), logger, environment-variable handling, media types, and the propagateAttributes context propagation utilities. Use @langfuse/tracing + @langfuse/otel for tracing and @langfuse/client for prompt management, datasets/experiments, and scores.

[!IMPORTANT] This is the current SDK generation (@langfuse/* scoped packages). The unscoped langfuse-core npm package belongs to the legacy v3 SDK. Migration guides: v3 → v4, v4 → v5.

Environment variables

Configuration shared across all @langfuse/* packages:

LANGFUSE_PUBLIC_KEY="pk-lf-..."
LANGFUSE_SECRET_KEY="sk-lf-..."
LANGFUSE_BASE_URL="https://cloud.langfuse.com" # 🇪🇺 EU region. 🇺🇸 US: https://us.cloud.langfuse.com, 🇯🇵 Japan: https://jp.cloud.langfuse.com, ⚕️ HIPAA: https://hipaa.cloud.langfuse.com

Packages

| Package | NPM | Description | Environments | | --------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------- | ------------ | | @langfuse/tracing | NPM | OpenTelemetry-based tracing instrumentation | Node.js 20+ | | @langfuse/otel | NPM | LangfuseSpanProcessor to export OpenTelemetry spans to Langfuse | Node.js 20+ | | @langfuse/client | NPM | Prompt management, datasets, experiments, scores, full REST API | Universal JS | | @langfuse/openai | NPM | observeOpenAI wrapper for tracing the OpenAI SDK | Universal JS | | @langfuse/langchain | NPM | CallbackHandler for LangChain / LangGraph tracing | Universal JS | | @langfuse/vercel-ai-sdk | NPM | Telemetry integration for Vercel AI SDK v7 | Universal JS | | @langfuse/browser | NPM | Browser score ingestion with public-key auth | Browser | | @langfuse/core | NPM | Shared core: generated API client, logger, utilities | Universal JS |

Documentation

  • Docs: https://langfuse.com/docs/observability/sdk/overview
  • Reference: https://js.reference.langfuse.com
  • LLM/agent-readable docs index: https://langfuse.com/llms.txt

License

MIT