The deciding difference is operational: Arize Phoenix can run on infrastructure you control, Pydantic Logfire cannot. If that constraint is real for you, it settles the choice before anything else is considered.
OpenTelemetry-native tracing and evals you can run locally.
OpenTelemetry observability with first-class Python and Pydantic AI support.
| Arize Phoenix | Pydantic Logfire | |
|---|---|---|
| Licence | Open source | Open source |
| Pricing | open source | freemium |
| Self-hostable | Yes | No |
| Languages | Python, TypeScript | Python, TypeScript |
| Install | pip install arize-phoenix | pip install logfire |
| Keys required | None | LOGFIRE_TOKEN |
The deciding difference is operational: Arize Phoenix can run on infrastructure you control, Pydantic Logfire cannot. If that constraint is real for you, it settles the choice before anything else is considered. Arize Phoenix: OpenTelemetry-native tracing and evals you can run locally. Pydantic Logfire: OpenTelemetry observability with first-class Python and Pydantic AI support.
Arize Phoenix can run on your own infrastructure. Pydantic Logfire is a hosted service only.
Arize Phoenix is open source (open source). Pydantic Logfire is open source (freemium).
Every page here answers to Accept: text/markdown and returns the same content at roughly a tenth the tokens. No separate site, no toggle — same URL.
curl -s -H "Accept: text/markdown" https://newagent.build/compare/phoenix-vs-logfire