Arize Phoenix

Open-source LLM tracing and evaluation platform designed for AI teams who need complete visibility into their applications. Built on OpenTelemetry standards, this platform offers vendor-agnostic monitoring without lock-in restrictions.

Key capabilities include:

• Automatic application tracing - Collect LLM app data with seamless instrumentation or manual control for detailed monitoring
• Interactive prompt playground - Fast sandbox environment for prompt iteration, model comparison, and debugging workflows
• Advanced evaluation tools - Pre-built templates with customization options plus human feedback integration
• Dataset clustering & visualization - Identify semantically similar content using embeddings to isolate performance issues
• Framework flexibility - Works with all major LLM tools and integrates into existing data science workflows

The platform has gained significant traction with 2.5M+ monthly downloads, 8k+ GitHub stars, and adoption by top AI teams. Users praise its ability to identify root causes of problematic responses, debug LLM workflows, and integrate observability directly into development processes.

Completely self-hostable with no feature restrictions, making it ideal for teams requiring full control over their AI monitoring infrastructure while maintaining transparency in model decision-making.