A agentindex
Comparison

Arize Phoenix vs LangSmith

A like-for-like, spec-level comparison. Both entries are verified against their docs and repo.

Arize Phoenix

Open-source LLM tracing and eval.

  • + Open source with OTel foundations
  • + Good LLM-as-a-judge evals built in
  • − Elastic license restricts some hosted offerings
  • − Enterprise features in the paid Arize cloud

LangSmith

LangChain's observability and eval platform.

  • + Best-in-class when you already use LangChain
  • + Strong tracing UX
  • − Proprietary and cloud-only
  • − Vendor lock-in to LangChain
Spec Arize Phoenix LangSmith
Category eval-observability eval-observability
License Elastic-2.0 Proprietary
Open source Yes No
Self-hostable Yes No
MCP support No No
Pricing free freemium
Starting price Self-host free Free developer tier
Models multi multi
Languages python, typescript python, typescript
GitHub stars 10.3k —
Last activity 2026-06-25 —