# Versions & Compatibility

Reference for how Langfuse's server, SDK, and API versions relate across Langfuse Cloud and self-hosted deployments.

| Date       | Langfuse Cloud | Self-hosted |  
|---|---|---|   
| Jan 2026  | v3  | v3 |   
| Apr 2026  | v3 + v4 preview   | v3 |   
| Jul 2026  | v4 (migration begins) | v4 |   
| Oct 2026  | v4           |   - |   
| Jan 2027  | -             | End of support for v3 |   
| Apr 2027  | -             | End of support for v4 |

## 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. |
| **Deprecated** | Still works but is superseded; removal is noted in the matrix below.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](https://github.com/langfuse/langfuse/releases) | [Observations-first data model](/content/docs/v4#what-changed/index.html); v3 continues to receive security patches |
| Python SDK | v4 | [`langfuse`](https://pypi.org/project/langfuse/) | OpenTelemetry-based since v3. Requires Python 3.9+. |
| JS/TS SDK | v5 | [`@langfuse/*`](https://www.npmjs.com/package/@langfuse/tracing) | OpenTelemetry-based since v4. Requires Node.js 20+. |
| Other languages | n/a | [OpenTelemetry](/content/integrations/native/opentelemetry/index.html) | 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**.

| Feature | Langfuse Cloud v3 (Deprecated as of Nov 16, 2026) | Langfuse Cloud v4 (GA) |
| --- | --- | --- |
| **Python** · [Upgrade guide](/content/docs/observability/sdk/upgrade-path/index.html) |  |  |
| Python SDK v4 | Full | Full |
| ▸Python SDK v3 | Full | Deprecated |
| ▸Python SDK v2 | Full | Deprecated |
| Python SDK v1 | Unsupported | Unsupported |

### FAQs

**I'm on Langfuse Cloud, which versions do I need to care about?**

Only your SDK version and the API endpoints you call. Langfuse Cloud always runs the latest server version, so self-hosted server minimums never apply to you. Keep your SDKs on the GA major version (Python v4, JS/TS v5) and migrate away from deprecated endpoints before the v4 cutover on **November 16, 2026**.

**I self-host Langfuse v3 and upgraded to Python SDK v4 / JS SDK v5, what works?**

Tracing, prompt management, datasets, and scores work fully (server ≥ 3.63.0). The default `api.observations` and `api.metrics` resources call v2 endpoints that require Langfuse v4; use the `api.legacy.*` resources until you upgrade your server to v4.

**My data takes minutes to show up in the UI, why?**

On the v4 data model, data from Python SDK < 4.7.0, JS SDK < 5.4.0, or OTel exporters without the `x-langfuse-ingestion-version: 4` header can be delayed by up to 15 minutes. Upgrade to Python SDK ≥ 4.7.0 / JS SDK ≥ 5.4.0 (or set the header) for real-time data.