MainStreet

MainStreet is a financial technology platform that helps startups and small businesses automate their back office and unlock hidden tax savings. Its AI-powered system scans payroll and accounting data to identify eligible federal, state, and local tax credits—including R&D tax credits—and manages the legal workflows to claim them. Beyond tax credits, MainStreet offers integrated bookkeeping, business banking, and financial management tools. The company was founded in 2019, acquired Capbase (company formation) in 2025, and was itself acquired by Employer.com in May 2025. It is headquartered in San Francisco, California.