# Arize Phoenix

> Arize Phoenix is a self-hostable LLM tracing and evaluation tool first released on 26 April 2023, built on OpenTelemetry and OpenInference; it is licensed under Elastic License 2.0 rather than Apache-2.0 or MIT, which permits free self-hosting but forbids reselling it as a competing hosted service.

OpenTelemetry-based LLM tracing and evaluation, licensed under ELv2.

- **Category:** Observability
- **License:** Elastic License 2.0 (ELv2)
- **Language:** Python
- **Self-hosted:** Yes
- **GitHub stars:** 11703 (2026-10-04)
- **Repository:** https://github.com/Arize-ai/phoenix
- **Last verified:** 2026-10-04

> Caveat: Sometimes mislabelled as Apache-2.0; the actual license is Elastic License 2.0, which is source-available rather than OSI open source.

Source: https://agent.c8.fit/tools/arize-phoenix/