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
Category	eval-observability	eval-observability
License	Elastic-2.0	Proprietary
Open source	Yes	No
Self-hostable	Yes	No
MCP support	No	No
Pricing	free	paid
Starting price	Self-host free	Custom (enterprise)
Models	multi	multi
Languages	python, typescript	python
GitHub stars	10.3k	—
Last activity	2026-06-25	—