Brex report identifies fastest-growing AI infrastructure startups

The summer 2026 Brex Benchmark report identifies the 25 fastest-growing software startups based on real credit card and bill pay activity from tens of thousands of customers. The data reveals a significant trend toward artificial intelligence infrastructure, with 14 of the 25 fastest-growing vendors providing the tools necessary to build AI products rather than the products themselves.

Together AI holds the top position by renting access to open models. Other high-growth sectors include databases, graphics processing units (GPUs), caches, and sandboxes that support the agent economy. This shift in startup spending patterns mirrors the previous era of mobile app dominance, which relied heavily on Amazon Web Services (AWS) infrastructure.

The rankings focus on growth acceleration among emerging companies, excluding publicly traded firms, those valued above $30 billion, or those exceeding $1 billion in annual recurring revenue (ARR).