Arize Phoenix
ObservabilitySource-available · Elastic License 2.0 (ELv2)★ 11,703（2026-10-04）Self-hosted
OpenTelemetry-based LLM tracing and evaluation, licensed under ELv2.
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.
Caveat: Sometimes mislabelled as Apache-2.0; the actual license is Elastic License 2.0, which is source-available rather than OSI open source.
Key facts
| Category | Observability |
|---|---|
| License | Elastic License 2.0 (ELv2) |
| Language | Python |
| Self-hosted | Yes |
| GitHub stars | 11,703 (2026-10-04) |
| Last push | 2026-10-04 |
| Last verified | 2026-10-04 |
| Repository | https://github.com/Arize-ai/phoenix |
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