The AI startups that customers will steadfastly part with money for are the ones that will ultimately survive and prosper.
While this may seem quite clear, it merits repeating in the AI industry’s financial landscape that is as warped as a funhouse mirror. ARR is far from dependable, as the SaaS-era metric has been diluted: In certain cases, companies incorporate pilot revenue and one-time deals to boost the appearance of stability. Meanwhile, there is a great deal of concern regarding what it means for an AI tool to provide genuine ROI.
Consequently, I was intrigued by fintech Brex’s recent data that outlines the 50 fastest-growing software vendors in 2025. The data is based on real spending, derived from credit card and bill pay transactions from over 35,000 anonymized Brex customers, and it shows exactly which AI tools and services those customers are willing to pay for.
The data places more emphasis on recent months to identify companies that didn’t simply experience a sudden surge and then plummet at the start of 2025. The data also excludes public companies and those worth more than $30 billion, so it covers the category of companies I am most worried about in the event of a bubble burst—the unicorns valued roughly between $5 and $25 billion. Big enough to matter, but not so big that they can’t fail.
“The aim isn’t just ‘who grew the most,’ but rather ‘who grew the most and is likely to keep growing,’” said Sumeet Marwaha, Brex’s head of data, via email.
The fastest-growing software vendor in 2025: Cursor, which is valued at over $29 billion, came in first. As the king of the coding powerhouses, Cursor saw a 1,000% year-over-year increase in spending among Brex customers. Marwaha stated that Cursor’s spending compounded every single month of 2025. He added, “No other vendor in our data did that. Not one.”
It wasn’t only Cursor—coding tools as a category made a significant showing in the top 50. Windsurf (acquired by Cognition after initially agreeing to a deal with OpenAI) ranked 6th, Replit 9th, CodeRabbit 15th, and StackBlitz 36th.
“This category practically didn’t exist two years ago,” Marwaha said. “Now there’s a paid, AI-powered coding environment that developers actually want and that managers are approving real budgets for.”
Marwaha said that the primary factor in that rapid ascent was “Friction. Or rather, the absence of it. Developers can run these tools locally. No IT approvals, no security reviews, no six-month procurement ordeal. Download it, use it, and see the value right away.”
Some other notable and surprising mentions: No. 2 was OpenRouter, a less well-known AI model marketplace, which saw a 1,500% year-over-year increase in spending on Brex. Other names drawing funds at the infrastructure layer include Vast.ai (11th), Groq (12th), Supabase (23rd), and Sentry (33rd).
The natural question, just a few days before Christmas, is how all of this will play out in 2026. Marwaha is betting on visual AI. In 2025, AI video production tool provider Kling.ai came in at 3rd, while Ideogram and Runway made the list at 17th and 44th respectively. The idea is that these visual and video platforms could follow the no-friction coding tool blueprint.
“The winners in 2026 won’t just be general-purpose generators,” Marwaha told . “They’ll be tools that nail a specific use case so well that teams can’t go back to the old way.”
See you tomorrow,
Allie Garfinkle
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