Arize Phoenix

What Arize Phoenix is

Arize Phoenix helps teams trace, evaluate, debug, and improve AI applications. It records model calls, retrieval, tool use, and custom logic in traces that can be sent over OpenTelemetry. Teams can score traces and spans with LLM-based evaluators, code checks, or human labels, and rerun datasets across application versions to compare evaluation results. Prompt tools include versioning, side-by-side testing, and replaying calls to inspect how prompt changes affect outputs. Documented integrations include LlamaIndex, LangChain, DSPy, OpenAI, Bedrock, and Anthropic; it can also use evaluation libraries such as Harbor, Ragas, Cleanlab, and MLflow. Phoenix runs locally or can be self-hosted using Docker, Kubernetes, or a cloud environment. Arize says self-hosting keeps traces in the user's own environment. Phoenix is free and open source under the ELv2 license, with users managing trace spans, ingestion volume, projects, and retention. It is built by Arize AI and the open-source community.