LangSmith vs Phoenix

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

	LangSmith Evaluation	Phoenix Evaluation
Tagline	LangChain's eval + observability platform.	Open-source LLM and agent observability platform with tracing, evals, and experimentation built on OpenTelemetry.
Category	Evaluation	Evaluation
Pricing	Freemium· Free starter; Plus $39/mo per seat	Freemium· Open source (ELv2) + free Phoenix Cloud; paid Arize AX for enterprise
Model	Platform (any LLM)	Multi-model
Editorial score	8.7 / 10	—
Use cases	LLM tracingevalsLangChain integration	llm-tracingagent-debuggingllm-evaluationprompt-experimentsrag-observability
Pros	Tight LangChain integration Strong tracing UX Mature dataset/eval flows Reasonable per-seat pricing	Genuinely open source (ELv2) with self-host parity, not a crippled OSS shell Native OpenTelemetry means no vendor lock-in for instrumentation Covers tracing, evals, annotation, and experiments in one tool Framework-agnostic: LangChain, LlamaIndex, DSPy, CrewAI, raw SDK calls all work
Cons	Best value if you're on LangChain UI can feel dense	Self-hosting still requires you to manage storage, retention, and upgrades Eval UX is less polished than some managed competitors like LangSmith Free cloud tier is capped at two instances
Website	www.langchain.com	phoenix.arize.com

Pick LangSmith if

Pick Phoenix if

✅ Genuinely open source (ELv2) with self-host parity, not a crippled OSS shell
✅ Native OpenTelemetry means no vendor lock-in for instrumentation
✅ Covers tracing, evals, annotation, and experiments in one tool
✅ Framework-agnostic: LangChain, LlamaIndex, DSPy, CrewAI, raw SDK calls all work