As AI investors worry about ROI, these startups have attracted significant amounts of money from customers in 2025.
The AI startups that customers will reliably pay for are the ones that will ultimately survive and thrive.
This seems pretty obvious, but it bears repeating in the financial landscape of AI industry mirrors. ARR remains far from reliable, as SaaS-era metrics have been watered down: In some cases, companies are cutting pilot revenues and one-time deals, reinforcing the appearance of stability. Meanwhile, there is a lot of concern about what it means for an AI tool to deliver true ROI.
So I was intrigued by recent data from Fintech Brex outlining the 50 fastest-growing software vendors in 2025. The data is based on actual spending, taken from the credit card and bill payment transactions of more than 35,000 anonymous Brex customers, which shows exactly who these customers are willing to pay for AI tools and services.
The data weighs more heavily on the later months to pick out companies that didn’t just skyrocket and collapse in early 2025. The data also filters out public companies and companies worth more than $30 billion, so it covers the category of companies that worries me the most in a bubble burst: unicorns valued, more or less, between $5 billion and $25 billion. Big enough to matter, but not big enough to fail.
“The goal is not just who has grown the most, but rather who has grown the most and who is likely to continue growing,” Brex data manager Sumeet Marwaha said by email.
Fastest Growing Software Company in 2025: Cursor, valued at over $29 billion, came in at number one. King of the coding giants, Cursor saw spending increase 1,000% year-over-year among Brex customers. Marwaha said Cursor has seen “spending increase every month of 2025. No other vendor in our data has done this. Not one.”
It wasn’t just Cursor: Coding tools as a category featured prominently in the top 50. Windsurf (acquired by Cognition after initially striking a deal with OpenAI) came in at No. 6, Replit at No. 9, CodeRabbit at No. 15, and StackBlitz at No. 36.
“This category didn’t exist two years ago,” Marwaha said. “There is now a paid, AI-powered coding environment that developers actually want and managers approve real budgets for. »
Marwaha said the main driver of this rapid increase was “friction. Or rather, the lack of it. Developers can run these tools locally. No IT approvals, no security review, no six-month procurement death march. Download it, use it, see the value immediately.”
Some other notable and surprising mentions: #2 was OpenRouter, a lesser-known AI model marketplace, which saw 1,500% year-over-year spending growth on Brex. Other names attracting infrastructure dollars include Vast.ai (No. 11), Groq (No. 12), Supabase (No. 23), and Sentry (No. 33).
The natural question, a few days before Christmas, is how all this will play out in 2026. Marwaha is betting on visual AI. In 2025, AI video production tool provider Kling.ai came in at No. 3, while Ideogram and Runway made the list at No. 17 and No. 44 respectively. The idea is that these visual and video platforms could follow the frictionless coding tool manual.
“The winners in 2026 won’t just be general-purpose generators,” Marwaha said. Fortune. “These will be tools that address a particular use case so well that teams won’t be able to go back to the old way. »
See you tomorrow,
Allie Garfinkle
X: @agarfinks
E-mail: alexandra.garfinkle@fortune.com
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Venture Capital Deals
– Cargoa San Francisco-based developer of an AI-powered network designed to monitor incoming and outgoing freight in the supply chain, has raised $42 million in Series B funding. Future led the tour and was joined by Lens Capital, Hearst Ventures, Light Bankand others.
– Truemedan Austin, Texas-based telehealth marketplace raised $34 million in Series A funding. Andreessen Horowitz led the tour and was joined by Bessemer Adventure Partners, Long Journey Businesses, Group of boxesAnd Trust Businesses.
Private equity
– Integrated Power Servicessupported by Projector Capital Partnersagreed to acquire TechPro Power Banda group of electrical service companies based in Crofton, Maryland. Financial terms were not disclosed.
– Vitruvius Partners acquired Aquabytea San Francisco, California-based developer of computer vision and machine learning software designed to improve fish farming efficiency. Financial terms were not disclosed.
Outings
– Alphabet agreed to acquire Cuta San Francisco-based energy infrastructure and data center company, for $4.75 billion. The acquisition includes TPG Increase The climate participation in society.
– Sand stream Capital agreed to acquire United Utility Servicesa utility company based in New Orleans, Louisiana and Charlotte, North Carolina, Bernhard Capital Partners. Financial terms were not disclosed.
– TPG agreed to acquire a majority stake in Servicea utility management company based in River Heights, Utah, Advent International. Financial terms were not disclosed.
