Fiddler AI vs LangSmith

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

	Fiddler AI Evaluation	LangSmith Evaluation
Tagline	Enterprise AI observability and guardrails platform for monitoring agents, LLMs, and ML models in production.	LangChain's eval + observability platform.
Category	Evaluation	Evaluation
Pricing	Enterprise· Tiered plans; contact sales	Freemium· Free starter; Plus $39/mo per seat
Model	Fiddler Centor (proprietary evaluators)	Platform (any LLM)
Editorial score	—	8.7 / 10
Use cases	llm-observabilityagent-monitoringai-guardrailsmodel-governancehallucination-detectioncompliance	LLM tracingevalsLangChain integration
Pros	Purpose-built for regulated industries with deep governance and audit features Inline guardrails enforce policy in real time on request/response paths Proprietary Centor evaluator models reduce LLM-as-judge cost Covers agents, LLMs, and classical ML in one control plane	Tight LangChain integration Strong tracing UX Mature dataset/eval flows Reasonable per-seat pricing
Cons	Enterprise sales motion; no transparent self-serve pricing Closed source with limited public technical detail Overkill for solo developers or small AI projects Setup and integration overhead vs. lightweight tracing tools	Best value if you're on LangChain UI can feel dense
Website	fiddler.ai	www.langchain.com

Pick Fiddler AI if

✅ Purpose-built for regulated industries with deep governance and audit features
✅ Inline guardrails enforce policy in real time on request/response paths
✅ Proprietary Centor evaluator models reduce LLM-as-judge cost
✅ Covers agents, LLMs, and classical ML in one control plane

Pick LangSmith if