A agentindex
Comparison

Arize Phoenix vs Fiddler

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

Fiddler

AI observability and governance for enterprise.

  • + Strong governance and compliance story
  • + Good for regulated enterprise
  • − Enterprise-priced
  • − Heavier than dev-focused tools
Spec Arize Phoenix Fiddler
Role Observability Observability
Tags observability, evaluation, persona-data-scientist, persona-platform-engineer observability, guardrails, persona-platform-engineer
License Elastic-2.0 Proprietary
Open source Yes No
Self-hostable Yes No
MCP support No No
Pricing free paid
Price Free tier Custom
Usage cost No model cost No model cost
Models multi multi
Languages python, typescript python
GitHub stars 10.4k —
Last activity 2026-07-04 —