CreditStud.io provides a free, open API for financial calculators. All endpoints return JSON, require no authentication, and support CORS for browser-based applications.
Overview
Base URL: https://creditstud.io/api/
All responses are JSON. No API key needed — just make GET requests. Example:
OpenAPI specification: openapi.json
Compare Credit Cards & BNPL
Compare the total cost of a purchase across credit cards and BNPL services, accounting for interest, fees, rewards, and introductory APR periods.
Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
amount | number | Yes | Purchase amount in dollars (e.g., 2000) |
months | integer | Yes | Payoff timeline in months (e.g., 12) |
score | integer | No | Credit score 300–850 (default: 720) |
category | string | No | Purchase category: restaurants, groceries, gas, travel, streaming, online, everything |
payment | number | No | Fixed monthly payment (overrides months-based calculation) |
Response
curl "https://creditstud.io/api/compare?amount=2000&months=12&score=720"
Rewards Calculator
Find the best credit card for your spending pattern. Calculates annual rewards value including signup bonuses.
Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
monthly | number | Yes | Total monthly spending in dollars (e.g., 3000) |
dining | number | No | Monthly dining spending |
groceries | number | No | Monthly grocery spending |
gas | number | No | Monthly gas spending |
travel | number | No | Monthly travel spending |
streaming | number | No | Monthly streaming spending |
curl "https://creditstud.io/api/rewards?monthly=3000&dining=300"
Debt Payoff Planner
Compare snowball vs avalanche strategies for paying off multiple debts. Returns month-by-month payoff schedules.
Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
debts | JSON array | Yes | URL-encoded JSON array of debts: [{"name":"Card A","balance":5000,"apr":22.24,"minPayment":150}] |
extraPayment | number | No | Extra monthly payment beyond minimums (default: 0) |
strategy | string | No | avalanche (default) or snowball |
curl "https://creditstud.io/api/debt-planner?debts=%5B%7B%22name%22%3A%22Card%20A%22%2C%22balance%22%3A5000%2C%22apr%22%3A22.24%2C%22minPayment%22%3A150%7D%5D"
Minimum Payment Calculator
See the devastating true cost of making only minimum payments — years of interest and thousands wasted.
Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
balance | number | Yes | Current balance in dollars |
apr | number | Yes | Annual percentage rate (e.g., 22.24) |
minPaymentPercent | number | No | Minimum payment as % of balance (default: 2) |
minPaymentFloor | number | No | Minimum payment floor in dollars (default: 25) |
curl "https://creditstud.io/api/min-payment?balance=5000&apr=22.24"
Card Data
Get structured data for all credit cards and BNPL services in our database. Useful for building your own tools or comparisons.
Returns all credit cards and BNPL services with terms, rates, and review links.
curl "https://creditstud.io/api/cards"
Returns interest rate tables by credit score tier. Each tier lists the typical APR range for that score range.
curl "https://creditstud.io/api/rates"
LLM Integration
CreditStud.io is designed to be discoverable and useful for AI agents and LLMs:
- OpenAPI spec: /.well-known/openapi.json — describes all API endpoints
- ChatGPT plugin manifest: /.well-known/ai-plugin.json — ready for ChatGPT integration
- llms.txt: /llms.txt — concise summary for LLM crawlers
- llms-full.txt: /llms-full.txt — detailed documentation for LLM crawlers
- Deep links: All calculator endpoints accept query parameters, so LLMs can construct URLs like
/compare/?amount=2000&months=12to pre-fill calculators - JSON responses: All API endpoints return structured JSON that LLMs can parse directly
Rate Limits & Fair Use
- No authentication required — just make requests
- CORS enabled — works from browsers and server-side
- Rate limit: 60 requests/minute per IP. Sustainable usage is fine; abuse is not.
- Data freshness: Card terms updated monthly. Check the
lastUpdatedfield in responses. - Disclaimer: All calculations are estimates. Verify terms with the issuing bank before making decisions.
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