Flex monetizes through payment volume

Free software means Flex is really selling a payment rail and a working capital product, not a SaaS seat. The more a customer runs card spend, bill pay, FX, and deposits through Flex, the more Flex earns, which makes product adoption and revenue expansion happen in the same motion. That is why a relatively small base of higher volume operators can support revenue per customer above typical SMB fintech levels.

• This model fits Flex’s customer base. Flex targets owner operated construction, trucking, logistics, and now displaced D2C businesses, where the pain is cash timing and large operating spend, not a need for lots of finance seats. A Net-60 card acts like a rolling working capital line, so routing more spend through Flex directly solves a daily cash problem.
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• The contrast with Mercury and Brex is where the money comes from. Mercury’s revenue is driven primarily by interest sharing on deposits, while Brex has been working to shift from a majority interchange model toward more software and AI platform revenue. Flex stays closer to the pure payments and credit side, with revenue scaling off transaction volume and usage fees.
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• That creates strong upside and strong concentration. Flex’s annualized revenue rose from $19M at the end of 2024 to $75M at the end of 2025, and the business appears to be driven by a smaller set of larger accounts. When one customer moves more spend, pays suppliers by card, or holds more cash on platform, revenue can jump fast without selling extra seats or modules.
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The next phase is likely deeper wallet share inside each account. If Flex keeps adding reasons to move AP, AR, cross border payments, and cash balances onto the platform, it can compound revenue from the same customer base in the same way payments companies do, while defending itself against bigger rivals that can copy software faster than they can win entrenched payment flows.