---
name: JS SDK
slug: langfuse-js-sdk
type: github
source_url: https://github.com/langfuse/langfuse-js
changelog_url: https://github.com/langfuse/langfuse-js/blob/HEAD/CHANGELOG.md
organization: Langfuse
organization_slug: langfuse
total_releases: 104
latest_version: v5.2.0-beta.2
latest_date: 2026-04-17
last_updated: 2026-04-19
tracking_since: 2024-05-01
canonical: https://releases.sh/langfuse/langfuse-js-sdk
organization_url: https://releases.sh/langfuse
---

<Summary type="rolling" window-days="90" release-count="7">
The SDK shipped v5.0.0 in early March with breaking changes, then stabilized through patch releases. The major version introduced structural changes documented in a migration guide, while subsequent releases fixed langchain integration issues—particularly around structured input handling in chain start events and content type checking in prompt clients—and added an option to disable logging entirely. Recent patches also synced API spec updates and addressed media handling in OpenTelemetry integration with AI SDK FilePart data.
</Summary>

<Summary type="monthly" period="March 2026" release-count="3">
The SDK shipped v5.0.0 as a major version bump with breaking changes requiring migration; see the upgrade documentation for details. Before the stable release, a beta landed fixes for OpenTelemetry's FilePart data handling in AI SDK media workflows and aligned the API spec with upstream changes.
</Summary>

<Release version="v5.2.0-beta.2" date="April 17, 2026" published="2026-04-17T14:16:55.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v5.2.0-beta.2">
**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v5.2.0-beta.1...v5.2.0-beta.2
</Release>

<Release version="v5.2.0-beta.1" date="April 17, 2026" published="2026-04-17T14:10:18.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v5.2.0-beta.1">
## What's Changed
* ci: add missing dependabot cooldown by @wochinge in https://github.com/langfuse/langfuse-js/pull/784
* fix(langchain): emit tool observations for LangChain tool runs by @hassiebp in https://github.com/langfuse/langfuse-js/pull/787
* ci(deps): bump the github-actions group with 2 updates by @dependabot[bot] in https://github.com/langfuse/langfuse-js/pull/788
* fix(ci): disable zizmor advanced security to unblock releases by @wochinge in https://github.com/langfuse/langfuse-js/pull/789
* fix(ci): allow for immutable GitHub releases by @wochinge in https://github.com/langfuse/langfuse-js/pull/790
* fix(ci): fix mutated workfile by @wochinge in https://github.com/langfuse/langfuse-js/pull/791


**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v5.2.0-beta.0...v5.2.0-beta.1
</Release>

<Release version="v5.2.0-beta.0" date="April 15, 2026" published="2026-04-15T08:22:10.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v5.2.0-beta.0">
## What's Changed
* feat(api): update API spec from langfuse/langfuse 07cae52 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/776
* chore(ci): optimize e2e langfuse server setup by @hassiebp in https://github.com/langfuse/langfuse-js/pull/777
* ci: add dependabot cooldown by @wochinge in https://github.com/langfuse/langfuse-js/pull/778
* ci(deps): bump github/codeql-action from 3.35.1 to 4.35.1 in the github-actions group across 1 directory by @dependabot[bot] in https://github.com/langfuse/langfuse-js/pull/780
* ci: harden GitHub Actions workflows with zizmor by @wochinge in https://github.com/langfuse/langfuse-js/pull/783


**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v5.1.0...v5.2.0-beta.0
</Release>

<Release version="v5.1.0" date="April 9, 2026" published="2026-04-09T16:56:44.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v5.1.0">
## What's Changed
* chore(deps-dev): bump happy-dom from 20.8.8 to 20.8.9 by @dependabot[bot] in https://github.com/langfuse/langfuse-js/pull/760
* chore(ci): move to blacksmith runners by @nimarb in https://github.com/langfuse/langfuse-js/pull/773
* feat(api): update API spec from langfuse/langfuse 1999706 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/774


**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v5.0.2...v5.1.0
</Release>

<Release version="v5.0.2" date="April 1, 2026" published="2026-04-01T11:05:55.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v5.0.2">
## What's Changed
* feat(api): update API spec from langfuse/langfuse b3adfc3 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/753
* fix(langchain): prevent handleChainStart from replacing structured input containing a "content" key by @taiichiro-nagase in https://github.com/langfuse/langfuse-js/pull/749
* Fix condition to check content type in promptClients by @budde377 in https://github.com/langfuse/langfuse-js/pull/751
* Add option to turn off logging by @szedelenyi in https://github.com/langfuse/langfuse-js/pull/752
* Fix string quotes in promptClients.ts by @budde377 in https://github.com/langfuse/langfuse-js/pull/755
* feat(api): update API spec from langfuse/langfuse a6c38c6 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/757
* chore(deps-dev): bump happy-dom from 20.0.2 to 20.8.8 by @dependabot[bot] in https://github.com/langfuse/langfuse-js/pull/759
* ci(GitHub actions): pin GitHub actions, configure dependabot alerts for GitHub actions by @wochinge in https://github.com/langfuse/langfuse-js/pull/761
* fix(langchain): handle null tokenUsage by @hassiebp in https://github.com/langfuse/langfuse-js/pull/769
* [codex] Fix local experiment ID stability by @hassiebp in https://github.com/langfuse/langfuse-js/pull/770

## New Contributors
* @taiichiro-nagase made their first contribution in https://github.com/langfuse/langfuse-js/pull/749
* @budde377 made their first contribution in https://github.com/langfuse/langfuse-js/pull/751
* @szedelenyi made their first contribution in https://github.com/langfuse/langfuse-js/pull/752
* @wochinge made their first contribution in https://github.com/langfuse/langfuse-js/pull/761

**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v5.0.1...v5.0.2
</Release>

<Release version="v5.0.1" date="March 13, 2026" published="2026-03-13T12:48:48.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v5.0.1">
## What's Changed
* feat(api): update API spec from langfuse/langfuse e84ca45 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/747


**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v5.0.0...v5.0.1
</Release>

<Release version="v5.0.0" date="March 10, 2026" published="2026-03-10T16:28:09.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v5.0.0">
# v5.0.0

## Breaking changes and migration guide

[Please see our documentation.](https://langfuse-docs-git-add-perf-changelog-langfuse.vercel.app/docs/observability/sdk/upgrade-path/js-v4-to-v5)

## What's Changed
* feat!: prepare v5 release by @hassiebp in https://github.com/langfuse/langfuse-js/pull/723
* feat(api): update API spec from langfuse/langfuse 784ab09 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/735
* feat(api): update API spec from langfuse/langfuse 25b5139 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/737
* fix(otel): skip base64 decode for URL-based FilePart data in AI SDK
   media handling by @Tanmay-24 in https://github.com/langfuse/langfuse-js/pull/736
* feat(api): update API spec from langfuse/langfuse a93f65a by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/738
* feat(api): update API spec from langfuse/langfuse 2eaf041 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/743
* fix(otel): allow async mask functions by @hassiebbot in https://github.com/langfuse/langfuse-js/pull/746

## New Contributors
* @Tanmay-24 made their first contribution in https://github.com/langfuse/langfuse-js/pull/736
* @hassiebbot made their first contribution in https://github.com/langfuse/langfuse-js/pull/746

**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.6.1...v5.0.0
</Release>

<Release version="v5.0.0-beta.1" date="March 2, 2026" published="2026-03-02T13:14:41.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v5.0.0-beta.1">
## Breaking changes
Please see the [preview migration guide](https://langfuse-docs-59h00s7jr-langfuse.vercel.app/docs/observability/sdk/upgrade-path/js-v4-to-v5) for full details.

## What's Changed
* feat(api): update API spec from langfuse/langfuse 784ab09 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/735
* feat(api): update API spec from langfuse/langfuse 25b5139 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/737
* fix(otel): skip base64 decode for URL-based FilePart data in AI SDK
   media handling by @Tanmay-24 in https://github.com/langfuse/langfuse-js/pull/736
* feat(api): update API spec from langfuse/langfuse a93f65a by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/738

## New Contributors
* @Tanmay-24 made their first contribution in https://github.com/langfuse/langfuse-js/pull/736

**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v5.0.0-beta.0...v5.0.0-beta.1
</Release>

<Release version="v5.0.0-beta.0" date="February 24, 2026" published="2026-02-24T18:40:09.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v5.0.0-beta.0">
## Breaking changes
Please see the [preview migration guide](https://langfuse-docs-59h00s7jr-langfuse.vercel.app/docs/observability/sdk/upgrade-path/js-v4-to-v5) for full details.


**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.6.1...v5.0.0-beta.0
</Release>

<Release version="v4.6.1" date="February 11, 2026" published="2026-02-11T13:45:23.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.6.1">
## What's Changed
* feat(api): update API spec from langfuse/langfuse 270f036 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/728
* feat(datasets): support running experiments on versioned datasets by @marliessophie in https://github.com/langfuse/langfuse-js/pull/727


**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.6.0...v4.6.1
</Release>

<Release version="v4.6.0" date="February 9, 2026" published="2026-02-09T12:19:34.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.6.0">
## What's Changed
* chore(deps-dev): bump @langchain/core from 1.0.1 to 1.1.8 by @dependabot[bot] in https://github.com/langfuse/langfuse-js/pull/712
* security: upgrade langchain by @maxdeichmann in https://github.com/langfuse/langfuse-js/pull/713
* feat(api): update API spec from langfuse/langfuse d59b6a3 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/714
* chore: update LICENSE by @marcklingen in https://github.com/langfuse/langfuse-js/pull/715
* feat(api): update API spec from langfuse/langfuse 41f064c by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/719
* feat(api): update API spec from langfuse/langfuse 99ffc45 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/720
* fix: move logger.debug with JSON stringify under if debug by @sumerman in https://github.com/langfuse/langfuse-js/pull/722
* feat(api): update API spec from langfuse/langfuse 966662e by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/726

## New Contributors
* @sumerman made their first contribution in https://github.com/langfuse/langfuse-js/pull/722

**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.5.1...v4.6.0
</Release>

<Release version="v4.5.1" date="December 19, 2025" published="2025-12-19T09:55:35.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.5.1">
## What's Changed
* feat(api): update API spec from langfuse/langfuse 3dbec46 by @langfuse-bot in https://github.com/langfuse/langfuse-js/pull/707


**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.5.0...v4.5.1
</Release>

<Release version="v4.5.0" date="December 17, 2025" published="2025-12-17T12:15:04.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.5.0">
## What's Changed
* feat(client): allow propagating traceName by @hassiebp in https://github.com/langfuse/langfuse-js/pull/706


**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.4.10...v4.5.0
</Release>

<Release version="v4.4.10" date="December 16, 2025" published="2025-12-16T18:02:43.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.4.10">
## What's Changed
* feat(prompts): allow prompt deletion by @nimarb in https://github.com/langfuse/langfuse-js/pull/703
* fix: send correct headers for self hosted gcs bucket media upload by @georgegebbett in https://github.com/langfuse/langfuse-js/pull/702
* fix(media): handle hostname check for GCS by @hassiebp in https://github.com/langfuse/langfuse-js/pull/704
* fix(experiments): pass item metadata to evaluators by @hassiebp in https://github.com/langfuse/langfuse-js/pull/705

## New Contributors
* @georgegebbett made their first contribution in https://github.com/langfuse/langfuse-js/pull/702

**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.4.9...v4.4.10
</Release>

<Release version="v4.4.10-alpha.3" date="December 5, 2025" published="2025-12-05T16:08:26.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.4.10-alpha.3">
## What's Changed
* feat(prompts): allow prompt deletion by @nimarb in https://github.com/langfuse/langfuse-js/pull/703


**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.4.10-alpha.2...v4.4.10-alpha.3
</Release>

<Release version="v4.4.10-alpha.2" date="December 3, 2025" published="2025-12-03T16:02:54.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.4.10-alpha.2">
**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.4.10-alpha.1...v4.4.10-alpha.2
</Release>

<Release version="v4.4.10-alpha.1" date="December 3, 2025" published="2025-12-03T15:45:43.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.4.10-alpha.1">
**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.4.10-alpha.0...v4.4.10-alpha.1
</Release>

<Release version="v4.4.10-alpha.0" date="December 3, 2025" published="2025-12-03T15:14:53.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.4.10-alpha.0">
**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.4.9...v4.4.10-alpha.0
</Release>

<Release version="v4.4.9" date="December 3, 2025" published="2025-12-03T15:05:31.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.4.9">
**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.4.8...v4.4.9
</Release>

<Release version="v4.4.8" date="December 3, 2025" published="2025-12-03T15:00:55.000Z" url="https://github.com/langfuse/langfuse-js/releases/tag/v4.4.8">
**Full Changelog**: https://github.com/langfuse/langfuse-js/compare/v4.4.7...v4.4.8
</Release>

<Pagination page="1" total-pages="6" total-items="104" next="https://releases.sh/langfuse/langfuse-js-sdk.md?page=2" />