xfingine

WebAssembly bindings for Xfingine — pure computation engines for personal finance planning.

Data in, arithmetic, data out. No UI, no network, no clock. The engines run entirely in your browser.

npm i xfingine

Usage

import init, { compute_emi, version } from 'xfingine';

await init();

const result = compute_emi({
  mode: 'emi',            // 'emi' | 'tenure' | 'loanAmount'
  loanAmount: 5_000_000,
  months: 240,
  interestRate: 9,        // percent per year
  inflationRate: 6,       // percent per year
  start: '2026-01',       // optional, enables dates + per-year breakdown
});

result.emi;                   // 44986   — the monthly payment
result.totals.nominalPaid;    // 10796818 — rupees actually debited
result.totals.realPaid;       // 6391327  — the same, in 2026 rupees
result.schedule;              // 240 rows, month by month
result.years;                 // 20 rows, one per calendar year

Every function has a _json twin that takes and returns a JSON string, for when you already have one in hand:

const json = compute_emi_json(JSON.stringify(request));

Invalid input throws a readable string:

try {
  compute_emi({ mode: 'tenure', loanAmount: 5_000_000, emi: 1000, interestRate: 12 });
} catch (e) {
  // "monthly payment of 1000.00 does not cover the first month's interest
  //  of 50000.00; the loan would never be repaid"
}

Conventions

• Money comes back as whole rupees (integers).
• Rates are percentages, not fractions: 9 means 9%.
• All keys are camelCase.
• Omit start and the engine reads no calendar at all — schedule rows carry no dates and years is empty.

Full documentation: github.com/xfina-dev/xfingine

License

Apache-2.0