FintechCalc

FintechCalc is a TypeScript financial calculation library focused on precision, modularity, and real-world finance features. It covers loan amortization, compound investment growth, insurance premium modeling, and core finance utilities.

Modules

Amortization

• Fully amortizing loans
• Interest-only loans
• Bullet loans
• Balloon loans by percentage or amortization period
• Adjustable interest rate schedules
• Extra payments and early payoff detection
• Mortgage features: fees, closing costs, PMI, escrow, and yearly breakdowns
• Input validation and negative amortization protection

Compound Interest

• Multiple compounding frequencies
• Recurring contributions
• Tax modeling for gains
• Inflation adjustment
• Nominal vs real return breakdown
• Detailed annual schedule output

Insurance

• Term life and whole life pricing
• Risk multipliers for health, occupation, and medical history
• Coverage decrease and inflation adjustment
• Rider support for accidental death benefit and waiver of premium
• Annual schedule projection

Finance Utilities

• Present Value (PV)
• Future Value (FV)
• Net Present Value (NPV)
• Internal Rate of Return (IRR)
• Effective Annual Rate (EAR)
• APR / nominal rate conversions

Usage

Import from the package entry point:

import {
  calculateAmortization,
  calculateInsurancePremium,
  presentValue,
  futureValue,
  netPresentValue,
  internalRateOfReturn,
  effectiveAnnualRate,
  nominalRateFromEffectiveAnnualRate
} from "./src";

Development

Run the test suite:

npm run test:run

Notes

The library uses decimal.js for high-precision calculations and is designed to be used as a logic layer behind frontend or backend applications.