Braintrust.
Evals and observability for AI products — Stripe-aligned investors, Notion and Coda customers.
What it is.
Braintrust is an evals-first AI engineering platform. Founded in 2023, funded by a16z and angels from Stripe, Notion, and Figma, used in production by Notion, Coda, Airtable, and Zapier. The product centres on evals — both LLM-judge and human-labelled — with tracing and prompt experimentation built around them. The opinionated choice for teams treating evals as the unit of progress.
Where it fits.
AI product teams that already understand evals matter and want a platform built around that conviction. Strong for buyers shipping production LLM features who need regression testing before each model swap. Less suited to teams still at the prototype stage where Helicone's proxy is faster to install.
- Evals-native — strongest workflow in the category
- Customer roster reads like the SaaS canon
- Self-hostable for regulated buyers
- Steeper learning curve than proxy-based observability
- Pricing climbs with event volume above the free tier
Frequently asked.
Why pick Braintrust over LangSmith?
Braintrust treats evals as the core primitive; LangSmith treats traces as the core primitive. Pick by which workflow your team needs to formalise first.
Which companies run Braintrust in production?
Notion, Coda, Airtable, Zapier, Vercel, and Replit have publicly disclosed Braintrust deployments. The investor list overlaps with the customer list.
Is on-prem deployment supported?
Yes on Enterprise. Used by regulated buyers and large enterprises that cannot send LLM traces to a third-party SaaS.
