Braintrust
AI eval and observability platform: tracing, LLM and human scoring, quality gates. Used by Vercel, Notion and Replit.
🔗 Visit Braintrust
Description
Companies that ship AI products need to know whether the AI's answers are actually good — and catch the bad ones before customers see them. Braintrust is a paid service that records everything your AI does, grades its answers, and can automatically block an update if quality drops: a quality-control lab for AI products.
Braintrust is an evaluation and observability platform for teams shipping production AI products. It ingests traces from AI applications — prompts, responses, tool calls — and layers three capabilities on top: tracing for real-time inspection with custom facets and task-specific views, evaluation where outputs are scored by LLM judges, code checks or human reviewers, and automation that turns those scores into quality gates capable of blocking a problematic release before it reaches users. Topics, its AI-powered pattern analysis, surfaces recurring failure modes from production traffic, and traces convert directly into evaluation datasets so regressions found in production become permanent test cases. Telemetry is stored in Brainstore, a proprietary database built for AI-specific data, and framework-agnostic SDKs cover Python, TypeScript, Go, Ruby and C#, with MCP integration. Customers include Vercel, Notion, Coursera, Dropbox, Replit and Graphite. Pricing is usage-based: a free Starter tier, a $249/month Pro plan plus data and scoring volume charges, and enterprise plans with on-premise or hosted deployment.
💬 Our review
The short version: one of the best 'quality control rooms' for teams whose product is built on AI — powerful and polished, but budget carefully because costs grow with usage.
Braintrust is what eval tooling looks like when it grows up into a platform: the trace-to-dataset loop is genuinely the right workflow (production failures become permanent test cases), quality gates give AI teams something like CI discipline, and the customer list — Vercel, Notion, Replit — is real validation, not logo-washing. The catch is cost predictability: $249/month for Pro is only the entry point, because data processing ($3-4/GB), scoring ($1.50-2.50 per 1k) and token charges stack on top, and AI telemetry volume grows faster than you expect. The 14-day retention on the free tier is tight for real debugging. It's also fully closed source with a proprietary datastore, so exporting your history has friction. Compare before committing: Langfuse self-hosted covers tracing and evals for free if you accept more assembly; promptfoo handles CI evals without a platform; Arize Phoenix is the open observability alternative. For funded teams where AI quality is the product, Braintrust is arguably the best-integrated option; for everyone else, start open source and graduate when the spreadsheet of scores stops scaling.
💰 Pricing
📊 Global score
🤖 AI-enriched data
Free tier; Pro $249/mo + usage (data, scores, tokens); enterprise custom
Pros
Trace-to-dataset eval loop
Quality gates block bad releases
SDKs in 5 languages
Cons
Usage costs hard to forecast
Closed source, proprietary datastore