📖 The AI Tool Bible

Kiln AI vs LangSmith

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

 
Kiln AI
Evaluation
LangSmith
Evaluation
TaglineOpen-source workbench for building, evaluating, and fine-tuning AI agents across 190+ models.LangChain's eval + observability platform.
CategoryEvaluationEvaluation
PricingFreemium· Free Individual tier; Team (request access); Enterprise (custom)Freemium· Free starter; Plus $39/mo per seat
ModelMulti-modelPlatform (any LLM)
Editorial score—8.7 / 10
Use cases
llm-evaluationfine-tuningagent-developmentsynthetic-dataragprompt-optimization
LLM tracingevalsLangChain integration
Pros
  • MIT-licensed Python library with 4,500+ GitHub stars
  • Local-first desktop app with Git-versioned datasets
  • Supports 190+ models across OpenAI, Anthropic, Gemini, Ollama, Bedrock
  • Covers build, eval, and fine-tune in one workbench
  • Genuine free tier, not a time-limited trial
  • Tight LangChain integration
  • Strong tracing UX
  • Mature dataset/eval flows
  • Reasonable per-seat pricing
Cons
  • Best Pro features (auto-optimization, AI assistant) are rate-limited on free tier
  • Team tier is request-access, not self-serve
  • Desktop-first means it's less collaborative than fully-hosted eval platforms
  • Best value if you're on LangChain
  • UI can feel dense
Websitekiln.techwww.langchain.com
Pick Kiln AI if
  • ✅ MIT-licensed Python library with 4,500+ GitHub stars
  • ✅ Local-first desktop app with Git-versioned datasets
  • ✅ Supports 190+ models across OpenAI, Anthropic, Gemini, Ollama, Bedrock
  • ✅ Covers build, eval, and fine-tune in one workbench
Pick LangSmith if
  • ✅ Tight LangChain integration
  • ✅ Strong tracing UX
  • ✅ Mature dataset/eval flows
  • ✅ Reasonable per-seat pricing
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