Braintrust
Braintrust is a LLM Evals and Observability company founded in 2023 and based in San Francisco, United States. It has raised $121M in total funding, most recently a Series B in 2026 at a $800M valuation.
End-to-end platform for LLM evaluations, prompt engineering, and production observability, used by Notion, Replit, Vercel, Cloudflare, Ramp and Stripe to ship AI features with confidence. Founded in 2023 by Ankur Goyal — previously founder of Impira (acquired by Figma) and an early ML lead at MemSQL — Braintrust gives AI engineers a single tool to author prompts, run offline evals, monitor production traces, and close the loop with human and LLM-as-judge scoring. The company raised an $80M Series B led by ICONIQ Capital at an $800M post-money valuation, bringing total funding to $121M from Greylock, a16z, ICONIQ, Elad Gil and Basecase.
Evals have become the new PRD for AI product teams, and Braintrust is the category-defining tool — every serious AI-native company in 2026 is either using it or building a worse version internally.
braintrust.dev ↗·LLM Evals and Observability·
United States·private 
