📖 The AI Tool Bible

LangSmith vs Promptfoo

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

 
LangSmith
Evaluation
Promptfoo
Evaluation
TaglineLangChain's eval + observability platform.Open-source eval and red-teaming framework for LLM apps, prompts, and RAG pipelines.
CategoryEvaluationEvaluation
PricingFreemium· Free starter; Plus $39/mo per seatFreemium· Open-source free; Enterprise SaaS contact sales
ModelPlatform (any LLM)Multi-model
Editorial score8.7 / 10—
Use cases
LLM tracingevalsLangChain integration
llm-evalsred-teamingprompt-regressionrag-testingai-securityci-cd-guardrails
Pros
  • Tight LangChain integration
  • Strong tracing UX
  • Mature dataset/eval flows
  • Reasonable per-seat pricing
  • Genuinely open source and self-hostable, not a fake-OSS funnel
  • Model-agnostic; works across OpenAI, Anthropic, local, custom APIs
  • Red-teaming covers prompt injection, jailbreaks, PII, policy violations
  • Clean CI integration with GitHub/GitLab/Jenkins for regression catching
  • Large community and Fortune-500 adoption signal staying power
Cons
  • Best value if you're on LangChain
  • UI can feel dense
  • YAML-heavy config has a learning curve for non-engineers
  • Enterprise pricing is opaque (contact sales only)
  • Red-team scans can be slow and token-expensive at scale
Websitewww.langchain.compromptfoo.dev
Pick LangSmith if
  • ✅ Tight LangChain integration
  • ✅ Strong tracing UX
  • ✅ Mature dataset/eval flows
  • ✅ Reasonable per-seat pricing
Pick Promptfoo if
  • ✅ Genuinely open source and self-hostable, not a fake-OSS funnel
  • ✅ Model-agnostic; works across OpenAI, Anthropic, local, custom APIs
  • ✅ Red-teaming covers prompt injection, jailbreaks, PII, policy violations
  • ✅ Clean CI integration with GitHub/GitLab/Jenkins for regression catching
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