Exact money math, in your browser.
Every cent is computed by an OCaml engine compiled to JavaScript: arbitrary-precision integers, banker's rounding on exact rationals, and a schedule you can audit line by line. Your data never leaves the device.
Monthly payment
Total interest
Total paid
EngineOCaml · exact
Amortization schedule
| # | Interest | Principal | Balance |
|---|
Final balance
Total deposited
Interest earned
EngineOCaml · exact
Final value
Effective annual rate
Periods
EngineOCaml · exact
Why OCaml?
Floating point can't represent 0.1 — so this app doesn't use it. The whole engine is integer arithmetic on big exact numbers, written in OCaml and compiled to plain JavaScript by js_of_ocaml.
The same source runs as a native binary in CI, where it must reproduce every golden result byte-for-byte before the bundle ships. Rounding follows the bankers' rule (half-to-even) applied to exact rationals — the same standard used by real accounting systems.