Arize Phoenix
Open-source LLM and agent tracing with built-in evaluation.
Open source
Best when the team needs observability that connects prompt debugging, agent traces, and evaluation in one open-source tool.
Selection advice
Choose Arize Phoenix when you want a single open-source pane for tracing and evaluation. It closes the loop from observation to improvement.
Best for
- agent tracing
- LLM observability
- evals
Not ideal for
- teams that already have a paid observability contract
- projects where traces are only needed for debugging, not evaluation
Core concepts
tracesspansevaluationsdatasets
Minimal implementation shape
Instrument your agent with Phoenix's OpenTelemetry integration, inspect traces in the UI, then create eval datasets from real production runs.