Enabling every company to be a fintech company.
Theorem is the embedded financial services platform that turns your customer base into a financial product line — branded accounts, cards, credit, and treasury — without a banking charter or a financial services team.
Your customers' money already moves through someone else
Every customer of yours holds a checking account at a bank you don't own, swipes a card you don't issue, draws working capital from a lender you don't underwrite, and parks idle cash in a treasury sweep you don't earn the spread on.
Theorem brings the four revenue lines that come with that activity — interchange, fees, net interest margin, and float — back inside your product. The license, the BSA/AML program, the card network membership, and the ledger sit on the platform side. What stays yours is the customer relationship and the revenue.
Architecture
Primitives
Four primitives. Four revenue lines.
Cards
InterchangeIssue branded debit and credit cards on the platform's BIN sponsor. Earn the interchange on every swipe; KYC, dispute handling, and ledger are platform-side.
Accounts
Fees & floatRun checking and savings under your brand. Charge maintenance fees on whatever schedule fits your customer; capture the float on idle balances.
Credit
UW yieldOriginate working capital, lines of credit, and term loans. Underwrite on the data your product already collects — not on a customer-supplied bank statement.
Treasury
SpreadSweep customer balances into yield-bearing instruments. Capture the spread between platform custody yield and the rate you pass through.
Three paths
Same revenue. Different prerequisites.
Integration
Each primitive runs standalone.
You don't have to ship the entire stack on day one. Start where your customers already lean in, then add the rest as the data flow earns the right to underwrite the next product.
Start with one primitive
Drop in cards alone, or accounts alone. KYC, ledger, and compliance run platform-side. Time to first transaction is measured in weeks, not regulatory cycles.
Add the next when adoption is real
Once one primitive has density, layer the next on the same SDK. No second integration; customers see one financial product family under your brand.
Compound the four
Card and account telemetry feeds credit underwriting; credit usage informs treasury sizing. The four products compound into a financial flywheel proprietary to your platform.
The playbook
Companies that already ran this play.
The pattern is well-established: own the customer relationship, then stack financial primitives on the data the relationship generates.
Shopify
Built Shopify Capital and Balance on top of merchant transaction data, turning a commerce platform into a top-100 SMB lender.
Toast
Layered Toast Capital and integrated payments on its restaurant POS, materially expanding gross profit per location.
Square
Cash App, Square Loans, and the Square Card extended a payments primitive into a full consumer-and-SMB financial product line.
Mercury
Built a banking experience purpose-fit for software startups by composing accounts, cards, treasury, and credit on a single platform.
Deliverables
What ships out of the box.
Checking & savings
FDIC-insured accounts under your brand. ACH, wires, bill pay, and balance APIs. End-customer dashboards optional.
Cards
Debit and credit, virtual and physical. BIN sponsor, network certification, dispute handling, and 1099 reporting included.
Credit
Working capital, lines of credit, and term loans. Decisioning APIs that consume your platform's telemetry as the underwriting input.
Treasury
Sweep, yield, FX, and multi-currency. Operator-side controls over allocation and customer-side rate pass-through.
You have the customers. Add the products.
Your platform already collects the data the underwriting needs. The SDK is the rest.