Compare software

TruLensLangfuse
Free

Free and open source.

 Freemium

Open source for self-hosting, with a hosted version that can be started for free.

Windows, macOS, Linux Web, Self-hosted
  • OpenTelemetry-native tracing of every agent step
  • Judges explain their scores, not just give numbers
  • Tracing, prompt management and evaluation in one tool
  • Can be self-hosted or used as a hosted service
  • Aimed at developers comfortable writing code
  • LLM judges add their own model calls and cost
  • Requires instrumenting your application with its SDK
  • Self-hosting means running and maintaining the server yourself
Downloadable app Self-hosted, Hosted service
Open source Open source
License not stated License not stated
Not stated if an account is needed Not stated if an account is needed
Not stated if it works offline Not stated if it works offline

Checked October 1, 2026

Checked September 26, 2026

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