📖 The AI Tool Bible

LangSmith vs Prompt Foundry

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

 
LangSmith
Evaluation
Prompt Foundry
Evaluation
TaglineLangChain's eval + observability platform.Prompt management and side-by-side LLM evaluation for OpenAI and Anthropic models.
CategoryEvaluationEvaluation
PricingFreemium· Free starter; Plus $39/mo per seatFreemium· Free tier (10 prompts, 500 evals/mo); Pro $15/user/mo; Enterprise custom
ModelPlatform (any LLM)OpenAI + Anthropic (multi-model)
Editorial score8.7 / 10—
Use cases
LLM tracingevalsLangChain integration
prompt-managementmodel-comparisonregression-testingtool-call-testingmultimodal-prompts
Pros
  • Tight LangChain integration
  • Strong tracing UX
  • Mature dataset/eval flows
  • Reasonable per-seat pricing
  • Genuinely usable free tier with GPT-4o-mini included, no API key required
  • Clean side-by-side comparison of OpenAI vs Anthropic models
  • Versioned deployed prompts you can pull from app code via SDK
  • Supports tool calls, variables, and vision inputs in tests
  • Self-hosted option available on Enterprise
Cons
  • Best value if you're on LangChain
  • UI can feel dense
  • Only OpenAI and Anthropic supported; no open-source or Gemini coverage
  • Lighter on dataset-driven eval and LLM-as-judge than Braintrust or LangSmith
  • Closed source; lock-in if you rely on hosted prompt storage
Websitewww.langchain.compromptfoundry.ai
Pick LangSmith if
  • ✅ Tight LangChain integration
  • ✅ Strong tracing UX
  • ✅ Mature dataset/eval flows
  • ✅ Reasonable per-seat pricing
Pick Prompt Foundry if
  • ✅ Genuinely usable free tier with GPT-4o-mini included, no API key required
  • ✅ Clean side-by-side comparison of OpenAI vs Anthropic models
  • ✅ Versioned deployed prompts you can pull from app code via SDK
  • ✅ Supports tool calls, variables, and vision inputs in tests
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