Arize Phoenix
Open-source, OpenTelemetry-based tracing and evaluation library that runs locally or self-hosted, serving as the OSS on-ramp to Arize's enterprise platform.
| Category | Observability & Tracing |
| Open source | Yes |
| Self-hostable | Yes |
| Pricing model | free |
| Pricing notes | Fully free OSS (Elastic License v2); hosted Phoenix Cloud has a free tier |
| Framework integrations | openai-sdk, langchain, llamaindex, dspy, opentelemetry, smolagents |
| Funding / ownership | Backed by Arize AI ($70M Series C, Feb 2025) |
Pricing/feature source: https://phoenix.arize.com