Humanloop vs Promptfoo
Updated March 10, 2026
Overview
Humanloop is a prompt engineering and evaluation platform that helps teams manage, version, and optimize LLM prompts. It provides prompt playgrounds, A/B testing, human feedback collection, and evaluation pipelines. Teams can track prompt performance across models and deploy optimized prompts to production.
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
- Collaborative platform for team development
- Version control for prompts
- A/B testing and evaluation tools
- Free tier for individuals
Cons
- Pro tier at USD 99/mo may be steep for small teams
- Learning curve for full feature utilization
- Requires commitment to platform workflow
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 Humanloop 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.