Company
Banking infrastructure for the platforms that power Main Street.
Mainstreetspine was founded in Atlanta to give vertical SaaS platforms the treasury infrastructure that banks never built for them — pre-assembled, API-first, and sized for real SMB businesses.
Mission
Treasury infrastructure shouldn't require a bank charter.
The vertical SaaS category is maturing. Fitness platforms, field service tools, salon software — the best of them have built deep operational workflows for their SMB customers. The next layer is financial. ACH disbursements, instant contractor payouts, payment plan management, revenue reconciliation. That layer requires banking infrastructure — FBO accounts, sub-ledger architecture, BSA/AML programs, KYB flows — that most SaaS engineering teams have never built and should never have to.
We built Mainstreetspine to be that layer. We're not a bank — we're a BaaS aggregator that abstracts Reg E, BSA/AML, and sub-ledger operations behind a clean API. We're not Stripe — we're the treasury layer your vertical SaaS embeds for end-customer accounts, with the FBO structure and compliance program that Stripe doesn't provide to SMB platforms.
What we stand for
Infrastructure, not middleware
We run the compliance stack, the bank relationships, the ledger. Not a wrapper.
Aligned incentives
Revenue share on transaction volume. We make money when your platform processes more.
Main Street-first
Our customers' customers are plumbers, gym owners, vet clinics. We design for that SMB reality.
Founding story
Built from inside the problem.
Devon spent six years at an Atlanta-based fintech building the sub-ledger systems that sit beneath consumer and small-business financial products — the unglamorous, mission-critical double-entry accounting layer that processes every debit, every credit, every reconciliation run. The institutional knowledge from that work: getting sub-ledger architecture right requires bank partner coordination, NACHA rule awareness, and compliance program ownership that very few SaaS engineers have ever touched.
The observation that became Mainstreetspine came from a conversation in late 2021. A founder building gym management software wanted to add ACH payouts for her studio operators — a natural next feature for a platform that already sat on top of member billing and instructor scheduling data. The path to live ACH ran through bank sponsorship agreements, FBO account legal structures, BSA/AML program documentation, beneficial ownership KYB flows, and NACHA originator classification for every gym on her platform. She said: "We can't build any of that. We just want the payout feature."
Devon left to build the answer. Mainstreetspine was incorporated in Atlanta in 2022 — not a Stripe plugin, not a white-labeled BaaS reseller, but a treasury infrastructure stack built specifically for the vertical SaaS platforms that serve independent gyms, HVAC contractors, nail salons, vet clinics, and landscaping companies. The SMBs that make up Main Street, served through the software platforms that run their operations.
Team
The people building the rails.
Devon Mitchell
CEO & Founder
Built sub-ledger and bank integration systems at an Atlanta fintech for six years before founding Mainstreetspine in 2022. Grew up in Buckhead. Writes occasionally about payment rail economics and the treasury gap facing vertical SaaS platforms.
Imani Foster
Head of Engineering
Seven years building payment API platforms before joining Mainstreetspine. Leads the REST API surface, webhook infrastructure, and SDK releases for Node, Python, and Ruby. Obsessive about idempotency and error response clarity.
Brett Calloway
Head of Compliance
Former BSA/AML officer at a Georgia community bank, then compliance at a fintech payments company. Owns the regulatory program at Mainstreetspine: banking partner relationships, NACHA originator compliance, OFAC screening procedures, and the KYB decision framework for every vertical we serve.
Tanya Osei
Head of Partnerships
Spent four years in go-to-market at vertical SaaS companies — field services and fitness — before moving to embedded finance. Runs partner onboarding at Mainstreetspine: from first call through sandbox to production launch. First point of contact for all pilot applications.
Atlanta
We picked Atlanta on purpose.
NCR anchored Atlanta's payments ecosystem for decades. Worldpay, Kabbage, Greenlight, and SilverSun grew in that soil. The result is a city with unusual depth in payments processing, community bank relationships, and fintech compliance talent — most of it invisible from the coasts. Devon built his foundational fintech knowledge here, and the banking partner relationships that run Mainstreetspine's infrastructure grew from this community.
We sit at 1180 Peachtree Street NE — Midtown Atlanta, near the Beltline and a short walk from the HVAC shops, nail salons, and independent gyms we ultimately serve. That's deliberate. When we say we're building for Main Street, we mean the actual street.
Ready to add treasury to your SaaS?
We work with a small number of vertical SaaS partners at a time — each integration gets direct attention from the team. Reach out and let's see if it's a fit.
Request a Pilot