Comparison

Arize Phoenix vs OpenLLMetry

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

OpenLLMetry

OpenTelemetry instrumentation for LLMs.

+ Vendor-neutral instrumentation
+ Works with existing observability stacks
− Instrumentation only, no UI
− Needs a backend like SigNoz or Honeycomb

Spec	Arize Phoenix	OpenLLMetry
Category	eval-observability	eval-observability
License	Elastic-2.0	Apache-2.0
Open source	Yes	Yes
Self-hostable	Yes	Yes
MCP support	No	No
Pricing	free	free
Starting price	Self-host free	Free
Models	multi	multi
Languages	python, typescript	python, typescript
GitHub stars	10.3k	7.2k
Last activity	2026-06-25	2026-06-25