Opik by Comet Review 2026

Open-source LLM evaluation and observability framework: trace, evaluate, monitor, and improve LLM applications.

Opik is the open-source LLM evaluation and observability tool from Comet, released under Apache 2.0. It exists because most teams building LLM apps end up reinventing the same instrumentation stack: trace every LLM call, score outputs, store prompts as first-class artifacts, run evaluation suites in CI, and detect regressions in production. Opik does all of that out of the box with a self-hostable backend and SDKs for Python, TypeScript, and Ruby. The core trace view captures every LLM call, tool call, and intermediate step in a tree, with token counts and costs attached. The evaluation framework lets you score outputs with code-based checks, heuristic metrics, or LLM-as-judge using a library of pre-built evaluators (hallucination, answer relevance, context recall, etc) plus custom ones. Prompts are versioned artifacts you can iterate on in a playground, deploy by name, and roll back. Production monitoring catches drift and quality regressions across deployments. Opik integrates with every popular framework: OpenAI, Anthropic, LangChain, LlamaIndex, LiteLLM, Haystack, CrewAI, AutoGen, DSPy, and others. There's a free hosted cloud at Comet, a self-hostable open-source backend, and Comet's commercial offering for teams that want managed Opik with SSO, RBAC, and longer retention.