LangSmith alternatives

The short answer

4 tools on this index are recorded as a substitute for LangSmith. 2 of these run the same way you already deploy LangSmith (saas), and 2 are permissively licensed, so they do not change what you can ship. All of them sit in Evaluation & Observability, so the choice is a real one rather than a category change. There is no overall winner here: which one is right depends on traffic shape, operational budget and how much of LangSmith you have already built around.

By Lattice editorial · Comparison reviewed 2026-09 · method

• Braintrustplatform · proprietary

  Evaluation platform with built-in scorers and a data flywheel.

  Use when Making evaluation, rather than tracing, the primary workflow.

  Skip when You need open formats and self-hosting.

• Langfuseplatform · MIT

  Self-hostable LLM tracing, prompt management and cost analytics.

  Use when Self-hostable tracing, prompts and evals in one place.

  Skip when You want a fully managed product with a support contract.

• Weights & Biasesplatform · proprietary

  Experiment tracking and model registry with LLM eval surfaces.

  Use when Experiment tracking and a model registry, with eval surfaces on top.

  Skip when You need an open, exportable format.

• Arize Phoenixlibrary · Apache-2.0

  Open-source tracing and evaluation built on OpenTelemetry.

  Use when OpenTelemetry-native evaluation you can run yourself.

  Skip when You want a vendor support contract behind it.