Braintrust vs Promptfoo
Updated March 10, 2026
Overview
Braintrust is an end-to-end AI product platform trusted by companies like Notion, Stripe, and Vercel. It combines logging, evaluation datasets, prompt management, and an AI proxy with automatic caching and fallback. Braintrust's evaluation framework helps teams measure quality across prompt iterations with customizable scoring functions.
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.
Key features
Core capabilities each platform advertises.
- Real-time LLM logging and tracing
- Built-in evaluation framework
- Prompt playground
- Dataset management
- Human review workflows
Strengths and tradeoffs
What each tool does well, and the limitations to keep in mind.
Pros
- Custom-built Brainstore database optimized for AI data with fast full-text search and low latency
- Framework agnostic with native SDKs for multiple languages and no vendor lock-in
- Comprehensive security and compliance certifications including SOC 2 Type II, GDPR, and HIPAA
- AI-assisted Loop Agent for automated optimization of prompts and evaluations
- Strong backing with $80M Series B funding and customers including Vercel, Notion, Coursera, and Dropbox
Cons
- Relatively new platform founded in 2022, less mature than some competitors
- Pro plan at $249/month may be expensive for smaller teams or individual developers
- Limited public information about advanced features and customization options
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
Braintrust or Promptfoo — which should you choose?
Choose Braintrust if you wantChoose if you want
- Iterating on prompts with real production data
- Running evaluations across model versions
- Building golden datasets from production traffic
- Human-in-the-loop review of LLM outputs
- Cost and latency optimization
Choose Promptfoo if you wantChoose if you want
Compare Braintrust 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.