# @langfuse/otel > Langfuse OpenTelemetry export helpers Latest version **6.0.1** (published 2026-10-19) · MIT license · 0 weekly downloads ## Install ```sh npm install @langfuse/otel pnpm add @langfuse/otel yarn add @langfuse/otel bun add @langfuse/otel ``` ## 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 | 1 | | Unpacked size | 196.2 KB | | Known vulnerabilities | 0 | | Install scripts | no | | Provenance | attested (GitHub Actions) | | GitHub stars | 169 | | Author | Langfuse | | Maintainers | bezbac, mdeichmann, marliessophie, hassieb, marcklingen, wochinge | ## Links - npm: https://www.npmjs.com/package/@langfuse/otel - 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/otel ## Dependencies (1) - [@langfuse/core](https://npm.io/package/@langfuse/core.md) ^6.0.1 ## 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 - … 60 more at https://npm.io/package/@langfuse/otel/versions ## README ![GitHub Banner](https://github.com/user-attachments/assets/5810ae13-15d6-4b60-afd2-927adc501861) # @langfuse/otel [Langfuse](https://langfuse.com) is the open-source LLM engineering platform: tracing & evaluation for LLM and agent applications, prompt management, datasets & experiments, and evaluation (scores). This package provides the **`LangfuseSpanProcessor`** — the OpenTelemetry span processor that exports spans to Langfuse with smart filtering, masking, and media upload. Register it with any OTel setup and spans from [`@langfuse/tracing`](https://www.npmjs.com/package/@langfuse/tracing), the Vercel AI SDK, or any other GenAI instrumentation are sent to Langfuse. Prompt management, datasets/experiments, and evals/scores live in [`@langfuse/client`](https://www.npmjs.com/package/@langfuse/client). > [!IMPORTANT] > This is the current SDK generation (`@langfuse/*` scoped packages). The unscoped `langfuse` npm package is the legacy v3 SDK — for new integrations use `@langfuse/tracing` + `@langfuse/otel`. 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). ## Install ```bash npm install @langfuse/otel @opentelemetry/sdk-trace-node ``` ## Environment variables ```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 ``` The batch byte limit applies to the final serialized OTLP/HTTP JSON request before compression. If a batch exceeds the limit, the entire batch is dropped; it is not split, retried, or truncated. Invalid values fall back to 64 MiB with a warning. Set the limit to a positive decimal safe integer; surrounding whitespace is ignored. Custom exporters passed to `LangfuseSpanProcessor` bypass this limit because they may use a different wire format or transport. The limit is approximate: it is compared against the batch's character count, which is never larger than the request, so a batch that fits is never dropped, but a sent request can be somewhat larger than the limit. Span exports are gzip-compressed by default on Node.js and Bun. To send uncompressed requests, set the `compression: "none"` option, `LANGFUSE_OTEL_COMPRESSION="none"`, or `OTEL_EXPORTER_OTLP_TRACES_COMPRESSION` / `OTEL_EXPORTER_OTLP_COMPRESSION` to `"none"`. ## Quickstart ```typescript import { LangfuseSpanProcessor } from "@langfuse/otel"; import { NodeTracerProvider } from "@opentelemetry/sdk-trace-node"; export const langfuseSpanProcessor = new LangfuseSpanProcessor(); const tracerProvider = new NodeTracerProvider({ spanProcessors: [langfuseSpanProcessor], }); tracerProvider.register(); ``` By default the processor exports Langfuse SDK spans, spans with `gen_ai.*`/`ai.*` attributes, and spans from known LLM instrumentation libraries — pass `shouldExportSpan` to override. **Serverless / short-lived environments** (Vercel, AWS Lambda, Cloudflare Workers, edge): pass `exportMode: "immediate"` so spans are not held in a batch, and `await langfuseSpanProcessor.forceFlush()` before the function instance is frozen or terminated (e.g. inside Vercel's `after()` or the platform's `waitUntil()`). Spans still buffered when the process exits are lost. ## 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 - Vercel AI SDK / Next.js guide: https://langfuse.com/integrations/frameworks/vercel-ai-sdk - 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/otel · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._