Versions & Compatibility
Reference for how Langfuse's server, SDK, and API versions relate across Langfuse Cloud and self-hosted deployments.
This part of the page is interactive; see it on the original page.
Langfuse v4 is generally available: self-hosted deployments upgrade with the v3 to v4 migration guide, and Langfuse Cloud, where v4 has been rolling out in preview since March 2026, will switch to v4 as the only experience, at which point remaining legacy APIs and ingestion paths are also removed.
The compatibility rule: each Langfuse server major version aims to support the current and the previous SDK major version of each language. New SDK versions require a recent server version, as some features may not be available on older servers; see the feature availability matrix.
We try very hard to uphold this rule. v4 breaks backwards compatibility with older SDKs; see the Langfuse v4 page for all information.
| Deployment | How versioning works |
|---|---|
| Langfuse Cloud | Always runs the latest Langfuse version; server versions are managed for you. Only your SDK version and the API endpoints you call matter; the self-hosted server minimums on this page do not apply. Breaking removals happen on published dates. |
| Self-hosted (OSS & Enterprise) | You choose when to upgrade the server. New capabilities are battle-tested on Langfuse Cloud before they ship in a self-hosted release, so Cloud can run ahead of the latest self-hosted version. SDK majors require the minimum server versions in the self-hosted compatibility matrix; breaking removals only happen in major server releases (see the versioning policy and upgrade documentation). |
Langfuse versions
Every Langfuse component (server, SDKs, and APIs) moves through these lifecycle stages:
| Stage | Meaning |
|---|---|
| Preview | New capabilities that are production-ready, but interfaces or API design may still change. |
| GA | Recommended and fully supported, including security patches. |
| Deprecated | Still works but is superseded; removal is noted in the matrix below. Migrate to the replacement. |
| End of life | Unsupported, no security patches. |
GA versions
| Component | GA version | Package / repo | Notes |
|---|---|---|---|
| Server | v4 | langfuse/langfuse  | Observations-first data model; self-hosted v3 receives security patches through January 31, 2027, then reaches end of life |
| Python SDK | v5 | langfuse  | OpenTelemetry-based since v3. Requires Python 3.11+ and Langfuse Cloud or self-hosted Langfuse v4.59.0+; see the v4 → v5 migration guide. |
| JS/TS SDK | v6 | @langfuse/*  | OpenTelemetry-based since v4. Requires Node.js 22+ and Langfuse Cloud or self-hosted Langfuse v4.59.0+; see the v5 → v6 migration guide. |
| Other languages | n/a | OpenTelemetry | Any OTel SDK to the Langfuse OTel endpoint |
Feature availability matrix
Langfuse Cloud runs v3 and v4 side by side until the v4 cutover on November 16, 2026 (2026-11-16). The v3 column is deprecated: everything marked Deprecated below keeps working until the cutover and is then removed. Click a row for details.
Self-hosting Langfuse? Use the self-hosted compatibility matrix instead; it covers each server version and the minimum server version per SDK.
| Feature | Langfuse Cloud v3 (Deprecated as of Nov 16, 2026) | Langfuse Cloud v4 (GA) |
|---|---|---|
| Python · Upgrade guide | ||
| Python SDK v5 | Unsupported | Full |
| Python SDK v4 | Full | Full |
| Python SDK v3 | Full | Deprecated |
| Python SDK v2 | Full | Deprecated |
| Python SDK v1 | Unsupported | Unsupported |
| JS/TS · Upgrade guide | ||
| JS/TS SDK v6 | Unsupported | Full |
| JS/TS SDK v5 | Full | Full |
| JS/TS SDK v4 | Full | Deprecated |
| JS/TS SDK v3 / v2 | Full | Deprecated |
| JS/TS SDK v1 | Unsupported | Unsupported |
| Third-party instrumentation · OpenTelemetry docs | ||
OpenTelemetry/api/public/otel/v1/traces | Full | Full |
Direct scores ingestion/api/public/scores | Full | Full |
SDK scores ingestionscore-create via /api/public/ingestion | Full | Full |
Legacy trace and observation events/api/public/ingestion | Full | Deprecated |
| Read APIs · Public API docs | ||
Observations API v2 & Metrics API v2/api/public/v2/... | Full | Full |
Scores API v3/api/public/v3/scores | Full | Full |
Deprecated read APIstraces, observations, sessions, scores, metrics, dataset runs | Full | Deprecated |
| Integrations & exports · Export docs | ||
| Blob storage export | Traces & observations | Enriched observations |
| PostHog integration | Traces & observations | Enriched observations |
| Mixpanel integration | Traces & observations | Enriched observations |
| Legacy export source (traces and observations) | Full | Deprecated |
| Evaluations · LLM-as-a-judge docs | ||
| Observation-level evaluators | Full | Full |
| Trace-level evaluators | Full | Deprecated |