LangSmith vs Promptfoo
Detailed side-by-side comparison to help you choose the right tool
LangSmith
🔴DeveloperAI Observability
LangSmith is LangChain's commercial observability, evaluation and prompt management platform for LLM apps and agents in production.
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FreePromptfoo
🔴DeveloperLLM Evaluation & Testing
Open-source LLM evaluation and red-teaming framework for testing prompts, models, and agents locally or in CI.
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FreeFeature Comparison
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💡 Our Take
Choose Promptfoo when you need security-oriented tests for prompts, RAG pipelines, agents, jailbreaks, and adversarial behavior before release. Choose LangSmith if your main workflow is tracing, debugging, and observing LangChain or LangGraph applications in development and production.
LangSmith - Pros & Cons
Pros
- ✓Best-in-class integration if you already use LangChain or LangGraph.
- ✓Eval suites are practical enough to actually gate releases on, not just dashboards.
- ✓Self-hosted Enterprise tier covers SOC 2 and regulated environments.
Cons
- ✗Per-trace pricing on Plus surprises teams that scale production traffic quickly.
- ✗Non-LangChain stacks work but trade ergonomic polish for SDK overhead.
- ✗Some eval features require additional LLM spend on top of the platform fee.
Promptfoo - Pros & Cons
Pros
- ✓Apache 2.0 local runner with CI-friendly configuration
- ✓Broad provider and assertion coverage
- ✓Evaluation and OWASP-oriented red teaming in one workflow
Cons
- ✗Good test datasets still require substantial human judgment
- ✗LLM-as-judge assertions add cost and evaluator bias
- ✗Hosted Team and Enterprise pricing is not publicly verified here
Not sure which to pick?
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