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Developer Portal

Power your app with Financial Intelligence

Connect to a suite of enterprise-grade financial calculators via our high-performance, developer-first REST API.

Quick Start

1. Get an API Key

Generate an API key from your dashboard to authenticate requests.

Manage API Keys →

2. Make Requests

Include your API key in the Authorization header.

Authorization: Bearer sk-...

Example Request

curl -X POST https://fincalculator.pro/api/v1/calculate/mortgage \
  -H "Authorization: Bearer sk-your-api-key" \
  -H "Content-Type: application/json" \
  -d '{
    "principal": 300000,
    "annual_rate": 6.5,
    "loan_term_years": 30
  }'

Rate Limits

TierLimitWindow
Starter100 requestsper day
Professional10,000 requestsper month
Enterprise100,000 requestsper month

Rate limit headers are included in all responses: X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset

Available Endpoints

v1.0.0 Stable
POST

Mortgage Calculator

Calculate monthly mortgage payments with amortization schedule

/api/v1/calculate/mortgage

Parameters

principalnumber
Req
annual_ratenumber
Req
loan_term_yearsnumber
Req
down_paymentnumber
property_tax_annualnumber
insurance_annualnumber
hoa_monthlynumber
POST

Loan EMI Calculator

Calculate loan EMI with full amortization schedule

/api/v1/calculate/loan

Parameters

principalnumber
Req
annual_ratenumber
Req
loan_term_monthsnumber
Req
POST

Auto Loan Calculator

Calculate auto loan with trade-in, sales tax, and fees

/api/v1/calculate/auto-loan

Parameters

vehicle_pricenumber
Req
annual_ratenumber
Req
loan_term_monthsnumber
Req
down_paymentnumber
trade_in_valuenumber
sales_tax_ratenumber
dealer_feesnumber
include_gap_insuranceboolean
gap_insurance_costnumber
POST

Savings Goal Calculator

Calculate required savings contributions to reach a goal

/api/v1/calculate/savings-goal

Parameters

target_amountnumber
Req
time_to_goal_monthsnumber
Req
current_savingsnumber
annual_return_ratenumber
contribution_frequencystring
POST

Credit Card Payoff Calculator

Calculate payoff timeline and interest savings

/api/v1/calculate/credit-card-payoff

Parameters

balancenumber
Req
annual_ratenumber
Req
minimum_paymentnumber
Req
fixed_paymentnumber
use_fixed_paymentboolean
POST

Investment Calculator

Calculate investment growth over time

/api/v1/calculate/investment

Parameters

initial_investmentnumber
Req
monthly_contributionnumber
annual_returnnumber
Req
investment_yearsnumber
Req
POST

Compound Interest Calculator

Calculate compound interest with different frequencies

/api/v1/calculate/compound-interest

Parameters

principalnumber
Req
annual_ratenumber
Req
yearsnumber
Req
compounding_frequencystring
POST

Retirement Calculator

Project retirement savings and income needs

/api/v1/calculate/retirement

Parameters

current_agenumber
Req
retirement_agenumber
Req
current_savingsnumber
Req
monthly_contributionnumber
Req
expected_returnnumber
Req
POST

Student Loan Calculator

Calculate student loan repayments (Standard or Graduated)

/api/v1/calculate/student-loan

Parameters

loanAmountnumber
Req
annualRatenumber
Req
yearsnumber
Req
repaymentTypestring
POST

Income Tax Calculator

Calculate 2026 Indian income taxes under the new regime

/api/v1/calculate/income-tax

Parameters

annualIncomenumber
Req
filingStatusstring
standardDeductionboolean
otherDeductionsnumber
stateTaxRatenumber
POST

SIP Calculator

Calculate future value of systematic investment plans

/api/calculators/sip

Parameters

monthlyInvestmentnumber
Req
annualRatenumber
Req
yearsnumber
Req
POST

Lumpsum Calculator

Calculate future value of one-time investments

/api/calculators/lumpsum

Parameters

principalnumber
Req
annualRatenumber
Req
yearsnumber
Req
POST

GST Calculator

Calculate Indian GST (Net, Gross, and Tax breakup)

/api/calculators/gst

Parameters

amountnumber
Req
gstRatenumber
Req
isInclusiveboolean
POST

Profit Margin Calculator

Calculate profit, margin, and markup

/api/calculators/profit-margin

Parameters

costnumber
Req
pricenumber
Req
quantitynumber
POST

Break-even Calculator

Calculate units and revenue needed to break even

/api/calculators/break-even

Parameters

fixedCostsnumber
Req
variableCostPerUnitnumber
Req
sellingPricePerUnitnumber
Req
POST

Property Appreciation Calculator

Calculate future property value based on annual appreciation rate

/api/v1/calculate/appreciation

Parameters

currentValuenumber
Req
yearsnumber
Req
annualGrowthRatenumber
Req
POST

Crypto Investment Calculator

Calculate potential crypto returns with high growth scenarios

/api/v1/calculate/crypto

Parameters

investmentAmountnumber
Req
currentPricenumber
Req
expectedAnnualGrowthnumber
Req
yearsnumber
Req
POST

Gold Investment Calculator

Calculate returns on physical or digital gold investments

/api/v1/calculate/gold

Parameters

initialWeightGramsnumber
Req
purchasePricePerGramnumber
Req
yearsnumber
Req
expectedAppreciationnumber
Req
makingChargesnumber
POST

Mutual Fund Calculator

Calculate SIP or Lumpsum returns with expense ratio impact

/api/v1/calculate/mutual-fund

Parameters

investmentTypestring
Req
amountnumber
Req
durationYearsnumber
Req
expectedReturnRatenumber
Req
expenseRationumber
POST

Property Tax Calculator

Calculate estimated annual property taxes

/api/v1/calculate/property-tax

Parameters

assessedValuenumber
Req
taxRatenumber
Req
POST

Rental Yield Calculator

Calculate gross and net rental yield for investment properties

/api/v1/calculate/rental-yield

Parameters

propertyValuenumber
Req
monthlyRentnumber
Req
annualExpensesnumber
Req
POST

Stamp Duty Calculator

Calculate stamp duty and registration charges for property purchase

/api/v1/calculate/stamp-duty

Parameters

propertyValuenumber
Req
stampDutyRatenumber
Req
registrationRatenumber
Req
otherChargesnumber

Response Format

Success Response

{
  "success": true,
  "data": {
    "monthly_payment": 1896.20,
    "total_interest": 382632.00,
    "amortization_table": [...]
  },
  "meta": {
    "calculation_time_ms": 5,
    "version": "1.0"
  }
}

Error Response

{
  "success": false,
  "error": "Validation error",
  "details": [
    {
      "field": "principal",
      "message": "Required"
    }
  ]
}

Status Codes

200
Success
400
Validation Error
401
Unauthorized
429
Rate Limited