v1.0 — Now Live
Financial Calculations
as a Service
Accurate tax, mortgage, and business math via a simple REST API. Integrate financial calculations into your app in minutes — no spreadsheets required.
Pricing
Start free. Scale when you need it.
Pro
$9/mo
- 1,000 requests/day
- All endpoints
- Priority support
- Usage analytics
Business
$29/mo
- 10,000 requests/day
- All endpoints
- SLA + priority support
- Usage analytics
Quick Start
Three steps: get a key, make a request, use the result.
curl
Python
JavaScript
# 1. Get your free API key curl "https://api.61tools.com/register?email=you@example.com" # 2. Calculate self-employment tax curl -X POST https://api.61tools.com/v1/tax/self-employment -H "Content-Type: application/json" -H "X-API-Key: YOUR_KEY" -d '{"net_income": 75000, "filing_status": "single"}' # Response { "se_tax": 10597.50, "se_tax_deduction": 5298.75, "net_earnings_for_se": 70687.50, "rate": "15.3%" }
AI Disclosure: Calculation logic in this API was developed with AI assistance. All formulas use standard financial and IRS-published methods. Results are for informational purposes only — consult a licensed tax professional or financial advisor for official guidance.
Endpoints
All POST endpoints accept JSON; all require X-API-Key header.
GET
/register?email=...
Get a free API key instantly — no email verification
POST
/v1/tax/self-employment
Self-employment tax (Schedule SE) — SE tax, deduction, net earnings
POST
/v1/tax/quarterly-estimate
Quarterly estimated tax payments — annual estimate + due dates
POST
/v1/finance/mortgage-payment
PITI mortgage payment — P&I, taxes, insurance, total interest
POST
/v1/finance/debt-payoff
Debt payoff timeline — months, total paid, total interest, payoff date
POST
/v1/business/break-even
Break-even analysis — units, revenue, contribution margin
POST
/v1/business/profit-margin
Gross, operating, and net profit margins
GET
/v1/usage
Your API key usage stats — requests today, limit, total