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
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
🔄 Alternatives to Braintrust
See all alternatives to Braintrust →❓ Frequently asked questions
- How is Braintrust different from Langfuse or promptfoo?
- Langfuse is open-source observability you can self-host free; promptfoo is free CLI/CI evals. Braintrust is a closed-source platform that integrates tracing, scoring, datasets and release-blocking quality gates in one product with a team UI.
- What does it actually cost in practice?
- Pro starts at $249/month, but real cost depends on usage: $3-4 per GB of processed trace data, $1.50-2.50 per 1,000 scores, plus tokens for AI-powered analysis. Model your trace volume before committing.
- Can outputs be scored by humans as well as LLMs?
- Yes — scoring supports LLM judges, code-based checks and human review queues, and the scores feed the same datasets and quality gates.
- Is there an on-premise option?
- Yes, enterprise plans offer hosted or on-premise deployment, with custom data retention.
- Is it worth the money compared to alternatives?
- Braintrust Pro is $249/month plus usage, versus Langfuse (open source, self-host free) and promptfoo (free). You're paying for the integrated loop — tracing, scoring, datasets and release gates in one UI. Worth it when AI quality directly drives revenue; hard to justify before product-market fit.
- Which eval/observability tool should you pick for your case?
- Funded team shipping an AI product: Braintrust. Budget-conscious or self-host requirement: Langfuse plus promptfoo. Deep in the LangChain ecosystem: LangSmith. Open-source observability standard with OTel: Arize Phoenix.