# @langfuse/core > Core functions and utilities for Langfuse packages Latest version **6.0.1** (published 2026-10-19) · MIT license · 0 weekly downloads ## Install ```sh npm install @langfuse/core pnpm add @langfuse/core yarn add @langfuse/core bun add @langfuse/core ``` ## Health **Score 75/100 (B)** — status: active. Positive: has types; esm support; no vulnerabilities; has provenance; recently updated; high maintenance score; high quality score. Warnings: low downloads. ## Facts | | | |---|---| | Version | 6.0.1 | | Published | 2026-10-19 | | First published | 2025-08-07 | | Weekly downloads | 0 | | License | MIT | | TypeScript types | bundled | | Module format | ESM + CommonJS | | Node | >=22 | | Dependencies | 0 | | Unpacked size | 4.2 MB | | Known vulnerabilities | 0 | | Install scripts | no | | Provenance | attested (GitHub Actions) | | GitHub stars | 170 | | Author | Langfuse | | Maintainers | bezbac, mdeichmann, marliessophie, hassieb, marcklingen, wochinge | ## Links - npm: https://www.npmjs.com/package/@langfuse/core - Repository: https://github.com/langfuse/langfuse-js - Homepage: https://github.com/langfuse/langfuse-js#readme - Issues: https://github.com/langfuse/langfuse-js/issues - npm.io page: https://npm.io/package/@langfuse/core ## Recent versions - 6.0.1 (latest) — 2026-10-19 - 5.5.0-beta.3 (beta) — 2026-06-18 - 4.4.10-alpha.3 (alpha) — 2025-12-05 - 6.0.0 — 2026-10-14 - 5.14.0 — 2026-10-14 - 5.13.1 — 2026-10-07 - 5.13.0 — 2026-10-05 - 5.12.1 — 2026-10-05 - 5.12.0 — 2026-10-05 - 5.11.1 — 2026-09-09 - 5.11.0 — 2026-08-27 - 5.10.2 — 2026-08-27 - 5.10.1 — 2026-08-17 - 5.10.0 — 2026-07-31 - 5.9.1 — 2026-06-30 - … 63 more at https://npm.io/package/@langfuse/core/versions ## README ![GitHub Banner](https://github.com/user-attachments/assets/5810ae13-15d6-4b60-afd2-927adc501861) # @langfuse/core [Langfuse](https://langfuse.com) 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`](https://www.npmjs.com/package/@langfuse/tracing) + [`@langfuse/otel`](https://www.npmjs.com/package/@langfuse/otel) for tracing and [`@langfuse/client`](https://www.npmjs.com/package/@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](https://langfuse.com/docs/observability/sdk/upgrade-path/js-v3-to-v4), [v4 → v5](https://langfuse.com/docs/observability/sdk/upgrade-path/js-v4-to-v5). ## Environment variables Configuration shared across all `@langfuse/*` packages: ```bash 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](https://github.com/langfuse/langfuse-js/tree/main/packages/tracing) | [![NPM](https://img.shields.io/npm/v/@langfuse/tracing.svg)](https://www.npmjs.com/package/@langfuse/tracing) | OpenTelemetry-based tracing instrumentation | Node.js 22+ | | [@langfuse/otel](https://github.com/langfuse/langfuse-js/tree/main/packages/otel) | [![NPM](https://img.shields.io/npm/v/@langfuse/otel.svg)](https://www.npmjs.com/package/@langfuse/otel) | `LangfuseSpanProcessor` to export OpenTelemetry spans to Langfuse | Node.js 22+ | | [@langfuse/client](https://github.com/langfuse/langfuse-js/tree/main/packages/client) | [![NPM](https://img.shields.io/npm/v/@langfuse/client.svg)](https://www.npmjs.com/package/@langfuse/client) | Prompt management, datasets, experiments, scores, full REST API | Universal JS | | [@langfuse/openai](https://github.com/langfuse/langfuse-js/tree/main/packages/openai) | [![NPM](https://img.shields.io/npm/v/@langfuse/openai.svg)](https://www.npmjs.com/package/@langfuse/openai) | `observeOpenAI` wrapper for tracing the OpenAI SDK | Universal JS | | [@langfuse/langchain](https://github.com/langfuse/langfuse-js/tree/main/packages/langchain) | [![NPM](https://img.shields.io/npm/v/@langfuse/langchain.svg)](https://www.npmjs.com/package/@langfuse/langchain) | `CallbackHandler` for LangChain / LangGraph tracing | Universal JS | | [@langfuse/vercel-ai-sdk](https://github.com/langfuse/langfuse-js/tree/main/packages/vercel-ai-sdk) | [![NPM](https://img.shields.io/npm/v/@langfuse/vercel-ai-sdk.svg)](https://www.npmjs.com/package/@langfuse/vercel-ai-sdk) | Telemetry integration for Vercel AI SDK v7 | Universal JS | | [@langfuse/browser](https://github.com/langfuse/langfuse-js/tree/main/packages/browser) | [![NPM](https://img.shields.io/npm/v/@langfuse/browser.svg)](https://www.npmjs.com/package/@langfuse/browser) | Browser score ingestion with public-key auth | Browser | | [@langfuse/core](https://github.com/langfuse/langfuse-js/tree/main/packages/core) | [![NPM](https://img.shields.io/npm/v/@langfuse/core.svg)](https://www.npmjs.com/package/@langfuse/core) | 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](https://github.com/langfuse/langfuse-js/blob/main/LICENSE) --- _Source: https://npm.io/package/@langfuse/core · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._