Braintrust has secured a $5.1m seed round led by Saam Motamedi from Greylock, bringing its total capital raised to $8.3m. The funding will help the company accelerate its vision of building world-class infrastructure for AI products, which have become critical infrastructure that powers AI at leading technology companies like Zapier, Coda, Airtable, and Instacart. Braintrust has built a toolkit for instrumenting code and running evaluations, enabling teams to assess, log, refine, and enhance their AI-enabled products as a core part of their dev loop. The company has seen significant growth since its last funding round just six weeks ago, doubling both its team and customer base. With this investment, Braintrust aims to address the challenge of "evals" in AI software development, which involves systematically measuring how well an AI system performs, often using context-specific data and metrics. By partnering with customers like Zapier, Coda, Airtable, and Instacart, Braintrust has helped users improve the accuracy of their systems by 30% or more, leading to faster ship cycles, increased product engagement, and better team collaboration. The funding will allow Braintrust to further develop its platform within the customer's cloud environment, ensuring it is safe to use for even the most data-sensitive tasks.