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MLflowPydantic Logfire
Free

Free and open source.

 Freemium

Free for 10 million spans, logs and metrics per month, no card required; paid plans above…

Web, Self-hosted, Command line Web
  • Tracing built on OpenTelemetry, independent of LLM provider
  • 50+ built-in evaluation metrics and LLM judges
  • Traces LLM calls alongside API and database activity
  • Built on OpenTelemetry with SQL querying
  • Broad feature set takes time to learn
  • Running it for a team means hosting and maintaining a server yourself
  • Primarily a hosted service requiring an account
  • Self-hosting is offered as an option rather than the default
Downloadable app, Self-hosted Web application, Hosted service
Open source Closed source
License: Apache-2.0 License not stated
No account needed Account needed
Not stated if it works offline Needs internet

Checked September 26, 2026

Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.