Fintech Calculator Platform
Financial calculator logic, structured API responses, scenario handling, validation, and maintainable business rules — exposed as an API the rest of the product can trust.
The math lived in spreadsheets.
Loan and financial scenarios were recalculated by hand for every client. Results drifted between analysts, nothing was auditable, and the logic couldn't be reused anywhere else in the product. Every change risked breaking an opaque chain of cells.
One engine, one source of truth, one API.
Swimstream built a calculator engine that holds the business rules in versioned, testable code. Scenarios are first-class objects; inputs are validated server-side; and every result returns through a structured API with predictable result codes and metadata.
Consistent figures the product can build on.
Numbers stopped drifting. The rule set became auditable and safe to evolve. Other features now call the calculator instead of re-implementing it — the logic exists in exactly one place.