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Best W&B Weave alternatives

5 tools developers use instead of W&B Weave, ranked by popularity. 5 offer a free plan and 3 are open source. Updated October 2026.

Free Open source Showing 1–5 of 5
  1. LangSmith logo

    LangSmith

    Free plan

    LangChain's observability and evaluation platform for LLM applications, tracing every step of a chain or agent run and scoring outputs against test datasets.

  2. Arize Phoenix logo

    Arize Phoenix

    Free plan Open source

    Open-source LLM observability and evaluation platform built on OpenTelemetry, with tracing, datasets, experiments and prompt tooling.

  3. Langfuse logo

    Langfuse

    Free plan Open source

    Open-source LLM observability platform for tracing, evaluating, and debugging prompts and agent runs, self-hostable or available as a managed cloud service.

  4. Braintrust logo

    Braintrust

    Free plan

    Evaluation-first platform for LLM applications, treating prompt and model changes like code changes that need regression tests before shipping.

  5. Helicone logo

    Helicone

    Free plan Open source

    Open-source LLM observability proxy that sits between your app and a model provider, logging requests, costs, and latency with a one-line integration change.