Affiniti’s 20- and 22-year-old founders raise $17M led by SignalFire just 6 months after an $11M seed

Affiniti founders Aaron Bai, 20, and Sahil Phadnis, 22, are building the kind of expense management software for main street small businesses that tech startups have enjoyed for years.

Their growth has been so impressive that six months after raising an $11 million seed round, they raised a $17 million Series A, led by Signal Fire, they told TechCrunch exclusively.

Affiniti offers SMBs like pharmacies, HVAC companies, and auto dealerships customizable expense management credit cards and software similar to the kind of wares pioneered by Brex…