MainStreet

Back Office Solutions for Small Business

San Francisco, United States · Founded 2019 · $60.0M raised

Employees
51–200
Founded
2019
Business Model
B2B
Total Funding
$60.0M
Last Round
$60.0M Series AMar 2021
Rounds
2

About

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.

Summary

MainStreet is a Fintech company based in San Francisco, United States, founded in 2019. It has raised $60.0M in total across 2 rounds, most recently a $60.0M Series A round in Mar 2021. Investors include Gradient Ventures, SignalFire and Reshape.

Tech & App Stack

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Funding History

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Investors

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