Langfuse
93 · HealthyTracing, evaluation and prompt management for LLM applications and agents.
Open source alternatives to LangSmith
3 open source projects replace LangSmith, ranked by how safe each is to depend on.
LangWatch
89 · HealthyObservability, evaluations and agent simulations for teams running LLM agents in production.
Helicone
67 · StableProxy-based LLM observability that logs requests, costs and latency with one line of setup.
Source-available and unverified licenses
The code for these is public, but the license is not an OSI open source license, or we have not verified it yet. Check the license notes on each project before relying on it.
Phoenix
77 · StableTracing and evaluation for LLM apps built on OpenTelemetry, with datasets and experiments.
At a glance
Health and license are separate verdicts: a project can be well maintained and still not be open source.
| Project | Health | License | Stars |
|---|---|---|---|
| Langfuse | 93 · Healthy | Free core, paid extrasMIT | 36k |
| LangWatch | 89 · Healthy | Free core, paid extrasApache-2.0 | 4.9k |
| Helicone | 67 · Stable | Free to useApache-2.0 | 6.2k |
| Phoenix | 77 · Stable | Free, no resellingElastic License 2.0 | 12k |
More in AI app builders
LangSmith is a paid AI app builders product. See all open source AI app builders tools, ranked the same way.
Scores last refreshed from GitHub on 9 October 2026. How we score.