Opik is Comet's open-source LLM evaluation and observability platform that provides comprehensive tracing, evaluation, and monitoring for LLM applications in development and production. It captures detailed traces of every LLM call, evaluation metrics, and user feedback — enabling teams to systematically measure quality, catch regressions, and improve AI application performance over time. AI engineering teams building production LLM applications use Opik to implement rigorous quality assurance practices — moving from ad hoc testing to systematic, reproducible evaluation workflows that ensure consistent, reliable AI behavior.