Versions & Compatibility - Langfuse
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| Deprecated | Still works but is superseded; removal is noted in the matrix below.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 | Observations-first data model; v3 continues to receive security patches |
| Python SDK | v4 | langfuse |
OpenTelemetry-based since v3. Requires Python 3.9+. |
| JS/TS SDK | v5 | @langfuse/* |
OpenTelemetry-based since v4. Requires Node.js 20+. |
| 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.
| Feature | Langfuse Cloud v3 (Deprecated as of Nov 16, 2026) | Langfuse Cloud v4 (GA) |
|---|---|---|
| Python · Upgrade guide | ||
| 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.