Opik vs Promptfoo
Updated March 10, 2026
Overview
Opik by Comet is an open-source LLM evaluation and observability platform. It provides tracing, evaluation scoring, dataset management, and experiment tracking for LLM applications. Opik supports automated LLM-as-judge evaluations and integrates with popular frameworks like LangChain and LlamaIndex.
Promptfoo is an open-source tool for testing and evaluating LLM prompts. It lets developers define test cases, run them against multiple models, compare outputs side-by-side, and catch regressions before deployment. Supports custom scoring functions, red-teaming, and CI/CD integration for automated prompt testing.
Strengths and tradeoffs
What each tool does well, and the limitations to keep in mind.
Pros
- Production-ready
- Good performance
- Active development
Cons
- Pricing varies
- Setup required
Pros
- Completely free and open source (MIT license)
- Fast with quality features like live reloads and caching
- Built-in red teaming and security vulnerability scanning
- Trusted by large companies with strong community
Cons
- CLI-focused creates friction for non-technical users
- Limited observability for complex production agents
- No version control for prompts, data, or metrics
- Offline nature hits ceiling for production scale
Compare Opik and Promptfoo on your own traffic
Respan lets you trace LLM and agent calls across any model or framework, A/B test prompts on production traffic, and route requests across 500+ models through one gateway.