📖 The AI Tool Bible

LangSmith vs W&B Weave

A side-by-side look at pricing, capabilities, pros, cons, and our editorial scores.

 
LangSmith
Evaluation
W&B Weave
Evaluation
TaglineLangChain's eval + observability platform.Production observability, tracing, and evaluation for LLM and agent systems from the Weights & Biases stack.
CategoryEvaluationEvaluation
PricingFreemium· Free starter; Plus $39/mo per seatFreemium· Free tier available; paid and enterprise plans via W&B
ModelPlatform (any LLM)Multi-model
Editorial score8.7 / 10—
Use cases
LLM tracingevalsLangChain integration
llm-tracingagent-observabilityonline-evaluationguardrailsregression-testingprompt-experimentation
Pros
  • Tight LangChain integration
  • Strong tracing UX
  • Mature dataset/eval flows
  • Reasonable per-seat pricing
  • Agent-native trace model with sessions, turns, tools, and sub-agents
  • Built-in scorers for toxicity, bias, PII, and hallucinations
  • Playground replays production traces against new prompts/models
  • Inherits the maturity of the W&B experiment-tracking platform
  • Broad SDK coverage across OpenAI, Anthropic, LangChain, LlamaIndex, DSPy
Cons
  • Best value if you're on LangChain
  • UI can feel dense
  • Pricing not transparent on the LLMOps landing page
  • Best value if you are already a W&B customer
  • Heavier than minimalist tracing tools for simple single-prompt apps
Websitewww.langchain.comwandb.ai
Pick LangSmith if
  • ✅ Tight LangChain integration
  • ✅ Strong tracing UX
  • ✅ Mature dataset/eval flows
  • ✅ Reasonable per-seat pricing
Pick W&B Weave if
  • ✅ Agent-native trace model with sessions, turns, tools, and sub-agents
  • ✅ Built-in scorers for toxicity, bias, PII, and hallucinations
  • ✅ Playground replays production traces against new prompts/models
  • ✅ Inherits the maturity of the W&B experiment-tracking platform
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