Within six months of an exit, serial entrepreneur and investor Ian Crosby was already imagining what he could build next. The ideas, he says, kept swirling in the back of his mind that he started a spreadsheet.

It wasn’t until he found himself prototyping in his Airbnb instead of sightseeing while in Europe that he’d get closer to the answer. When a startup that he met with recommended that he try ElevenLabs—a platform that lets users build and launch AI agents that can talk, type, and take other actions across phone, web, and apps—he created his own with a British accent that started off as “hugely entertaining,” he says, until the idea hit him: an accounting system that’s fully autonomous.

An agent that does a software company’s bookkeeping from start to finish without any staff. It would connect to their bank accounts, payroll sys ...