Financial API Suite

Production-ready APIs for currency conversion, IBAN validation, and business day calculations. Built on Cloudflare Workers for sub-100ms global response times.

99.9% Uptime Sub-100ms Latency 170+ Currencies

Currency Converter API

Real-time exchange rates for 170+ currencies. Convert amounts, retrieve historical rates, time series data, and fluctuation analysis.

Base URL: https://aihowtoinvest.com/currency-api/v1
GET /v1/convert Convert an amount between two currencies ▶
Parameters
NameTypeDescription
from requiredstringSource currency code (e.g., USD)
to requiredstringTarget currency code (e.g., EUR)
amount requirednumberAmount to convert
cURL
JavaScript
Python
# Convert 100 USD to EUR
curl "https://aihowtoinvest.com/currency-api/v1/convert?from=USD&to=EUR&amount=100" \
  -H "X-API-Key: YOUR_API_KEY"
// JavaScript
const res = await fetch(
  'https://aihowtoinvest.com/currency-api/v1/convert?from=USD&to=EUR&amount=100',
  { headers: { 'X-API-Key': 'YOUR_API_KEY' } }
);
const data = await res.json();
console.log(data.data.result); // 92.15
# Python
import requests
r = requests.get(
    'https://aihowtoinvest.com/currency-api/v1/convert',
    params={'from': 'USD', 'to': 'EUR', 'amount': 100},
    headers={'X-API-Key': 'YOUR_API_KEY'}
)
print(r.json()['data']['result'])
Response
{
  "success": true,
  "data": {
    "from": "USD",
    "to": "EUR",
    "amount": 100,
    "rate": 0.9215,
    "result": 92.15,
    "timestamp": "2026-04-02T12:00:00Z"
  }
}
GET /v1/rates Get exchange rates for a base currency ▶
Parameters
NameTypeDescription
base optionalstringBase currency code (default: USD)
symbols optionalstringComma-separated target currencies (e.g., EUR,GBP,JPY)
cURL
JavaScript
curl "https://aihowtoinvest.com/currency-api/v1/rates?base=USD&symbols=EUR,GBP,JPY" \
  -H "X-API-Key: YOUR_API_KEY"
const res = await fetch(
  'https://aihowtoinvest.com/currency-api/v1/rates?base=USD&symbols=EUR,GBP,JPY',
  { headers: { 'X-API-Key': 'YOUR_API_KEY' } }
);
const data = await res.json();
Response
{
  "success": true,
  "data": {
    "base": "USD",
    "rates": {
      "EUR": 0.9215,
      "GBP": 0.7892,
      "JPY": 149.85
    },
    "timestamp": "2026-04-02T12:00:00Z"
  }
}
GET /v1/currencies List all supported currencies ▶

No authentication required. Returns all 170+ supported currency codes with names.

cURL
curl "https://aihowtoinvest.com/currency-api/v1/currencies"
GET /v1/historical Get rates for a specific date ▶
Parameters
NameTypeDescription
date requiredstringDate in YYYY-MM-DD format
base optionalstringBase currency (default: USD)
symbols optionalstringComma-separated currencies
cURL
curl "https://aihowtoinvest.com/currency-api/v1/historical?date=2026-01-15&base=USD&symbols=EUR,GBP" \
  -H "X-API-Key: YOUR_API_KEY"
GET /v1/timeseries Get daily rates between two dates ▶
Parameters
NameTypeDescription
start_date requiredstringStart date (YYYY-MM-DD)
end_date requiredstringEnd date (YYYY-MM-DD)
base optionalstringBase currency (default: USD)
symbols optionalstringComma-separated currencies
cURL
curl "https://aihowtoinvest.com/currency-api/v1/timeseries?start_date=2026-03-01&end_date=2026-03-31&base=USD&symbols=EUR" \
  -H "X-API-Key: YOUR_API_KEY"
GET /v1/fluctuation Get rate changes over a period ▶
Parameters
NameTypeDescription
start_date requiredstringStart date (YYYY-MM-DD)
end_date requiredstringEnd date (YYYY-MM-DD)
base optionalstringBase currency (default: USD)
symbols optionalstringComma-separated currencies
cURL
curl "https://aihowtoinvest.com/currency-api/v1/fluctuation?start_date=2026-03-01&end_date=2026-03-31&base=USD&symbols=EUR,GBP" \
  -H "X-API-Key: YOUR_API_KEY"

IBAN Validator API

Validate international bank account numbers, extract bank details, generate test IBANs, and look up BIC/SWIFT codes. Supports 80+ countries.

Base URL: https://aihowtoinvest.com/iban-validator
GET /validate Validate an IBAN and extract components ▶
Parameters
NameTypeDescription
iban requiredstringThe IBAN to validate (spaces allowed)

Authentication: X-API-Key header or ?apikey= query parameter

cURL
JavaScript
Python
curl "https://aihowtoinvest.com/iban-validator/validate?iban=DE89370400440532013000" \
  -H "X-API-Key: YOUR_API_KEY"
const res = await fetch(
  'https://aihowtoinvest.com/iban-validator/validate?iban=DE89370400440532013000',
  { headers: { 'X-API-Key': 'YOUR_API_KEY' } }
);
const data = await res.json();
console.log(data.valid, data.country, data.bankCode);
import requests
r = requests.get(
    'https://aihowtoinvest.com/iban-validator/validate',
    params={'iban': 'DE89370400440532013000'},
    headers={'X-API-Key': 'YOUR_API_KEY'}
)
print(r.json())
Response
{
  "valid": true,
  "iban": "DE89370400440532013000",
  "country": "Germany",
  "countryCode": "DE",
  "checkDigits": "89",
  "bankCode": "37040044",
  "accountNumber": "0532013000",
  "length": 22,
  "sepa": true
}
GET /generate Generate a test IBAN for a country ▶
Parameters
NameTypeDescription
country requiredstringISO 3166-1 alpha-2 country code (e.g., DE, GB, FR)
bankCode optionalstringSpecific bank code to use
cURL
curl "https://aihowtoinvest.com/iban-validator/generate?country=DE" \
  -H "X-API-Key: YOUR_API_KEY"
GET /countries List all supported countries ▶

No authentication required. Returns all supported countries with IBAN format details.

cURL
curl "https://aihowtoinvest.com/iban-validator/countries"
GET /bic Look up BIC/SWIFT code from IBAN ▶
Parameters
NameTypeDescription
iban requiredstringThe IBAN to look up
cURL
curl "https://aihowtoinvest.com/iban-validator/bic?iban=DE89370400440532013000" \
  -H "X-API-Key: YOUR_API_KEY"
POST /batch Validate up to 100 IBANs at once ▶

Send a JSON body with an array of IBANs. Maximum 100 per request.

cURL
curl -X POST "https://aihowtoinvest.com/iban-validator/batch" \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"ibans": ["DE89370400440532013000", "GB29NWBK60161331926819"]}'

Business Day API

Calculate business days between dates, check holidays, and add/subtract working days. Supports 20+ countries with public holiday calendars.

Base URL: https://aihowtoinvest.com/business-day-api
GET /is-business-day Check if a date is a business day ▶
Parameters
NameTypeDescription
date requiredstringDate in YYYY-MM-DD format
country optionalstringCountry code (default: US)
cURL
JavaScript
curl "https://aihowtoinvest.com/business-day-api/is-business-day?date=2026-12-25&country=US" \
  -H "X-API-Key: YOUR_API_KEY"
const res = await fetch(
  'https://aihowtoinvest.com/business-day-api/is-business-day?date=2026-12-25&country=US',
  { headers: { 'X-API-Key': 'YOUR_API_KEY' } }
);
const data = await res.json();
Response
{
  "date": "2026-12-25",
  "country": "US",
  "isBusinessDay": false,
  "isWeekend": false,
  "isHoliday": true,
  "holidayName": "Christmas Day",
  "dayOfWeek": "Friday"
}
GET /add Add/subtract business days to a date ▶
Parameters
NameTypeDescription
date requiredstringStart date (YYYY-MM-DD)
days requiredintegerNumber of business days to add (negative to subtract)
country optionalstringCountry code (default: US)
cURL
curl "https://aihowtoinvest.com/business-day-api/add?date=2026-04-01&days=10&country=US" \
  -H "X-API-Key: YOUR_API_KEY"
GET /between Count business days between two dates ▶
Parameters
NameTypeDescription
start requiredstringStart date (YYYY-MM-DD)
end requiredstringEnd date (YYYY-MM-DD)
country optionalstringCountry code (default: US)
cURL
curl "https://aihowtoinvest.com/business-day-api/between?start=2026-01-01&end=2026-12-31&country=US" \
  -H "X-API-Key: YOUR_API_KEY"
GET /next-business-day Get the next business day after a date ▶
Parameters
NameTypeDescription
date requiredstringReference date (YYYY-MM-DD)
country optionalstringCountry code (default: US)
cURL
curl "https://aihowtoinvest.com/business-day-api/next-business-day?date=2026-12-24&country=US" \
  -H "X-API-Key: YOUR_API_KEY"
GET /holidays List public holidays for a year and country ▶
Parameters
NameTypeDescription
year requiredintegerYear (1970-2100)
country requiredstringCountry code (e.g., US, GB, DE)
cURL
curl "https://aihowtoinvest.com/business-day-api/holidays?year=2026&country=US" \
  -H "X-API-Key: YOUR_API_KEY"
GET /countries List all supported countries ▶

No authentication required. Returns all supported countries with holiday counts.

cURL
curl "https://aihowtoinvest.com/business-day-api/countries"

Authentication

All API endpoints require authentication via an API key. You can pass it in two ways:

Header (recommended)

X-API-Key: YOUR_API_KEY

Query Parameter

?apikey=YOUR_API_KEY

Rate Limiting

Rate limits are enforced per API key. When you exceed your limit, the API returns a 429 Too Many Requests response with X-RateLimit-Remaining and X-RateLimit-Reset headers.

Error Handling

All errors return a consistent JSON format:

{
  "error": "Description of what went wrong"
}
StatusDescription
400Bad Request -- invalid parameters
401Unauthorized -- missing or invalid API key
429Too Many Requests -- rate limit exceeded
500Internal Server Error

Simple, Transparent Pricing

Start free, scale as you grow. All plans include access to every API.

Free

$0
forever
  • 100 requests per day
  • All 3 APIs included
  • Standard response times
  • Community support
  • CORS enabled
Get Free Key

Pro

$9.99
per month
  • 10,000 requests per day
  • All 3 APIs included
  • Priority response times
  • Email support
  • Batch endpoints
  • Rate limit headers
Get Pro Key

Enterprise

Custom
contact us
  • Unlimited requests
  • All 3 APIs included
  • Dedicated support
  • SLA guarantee
  • Custom integrations
  • On-premise options
Contact Sales

Get Your API Key

Start building with our financial APIs in minutes. Free tier requires no credit card.

Get Key on RapidAPI Contact for Enterprise

Understanding Financial APIs

What is a Financial API?

A financial API (Application Programming Interface) is a REST-based web service that lets developers programmatically access financial data and calculations. Instead of building complex currency databases, IBAN validation logic, or holiday calendars from scratch, developers send HTTP requests to an API endpoint and receive structured JSON responses in milliseconds. Financial APIs power everything from fintech apps and banking platforms to e-commerce checkout flows and accounting software.

Currency Converter API Use Cases

Currency conversion APIs are essential infrastructure for any application that handles international money. Common use cases include:

IBAN Validation for Payment Processing

IBAN (International Bank Account Number) validation is a critical step in payment processing workflows. Validating IBANs before initiating wire transfers helps prevent failed transactions, reduces costly return fees, and protects against fraud. An IBAN validation API checks the format, length, country code, and check digits algorithmically, then extracts the bank code and account number for downstream processing. Batch validation endpoints allow payment platforms to verify hundreds of IBANs in a single request, essential for payroll processing and bulk disbursements.

Business Day Calculation

Accurately calculating business days is essential for payroll systems, trade settlement (T+1/T+2 rules), SLA tracking, and delivery date estimation. A business day API accounts for weekends and country-specific public holidays so your application does not need to maintain its own holiday calendar. Use cases include calculating payment due dates, estimating settlement windows for securities trades, and scheduling recurring invoices on working days only.

Frequently Asked Questions

Is there a free tier for these financial APIs?

Yes. The free plan includes 100 requests per day across all three APIs (Currency Converter, IBAN Validator, and Business Day Calculator) with no credit card required. This is sufficient for personal projects, prototyping, and low-traffic applications.

How often are exchange rates updated?

Exchange rates are updated multiple times per day from institutional-grade data sources. The timestamp field in each response indicates when the rate was last refreshed, so your application always knows how current the data is.

Which countries does the IBAN Validator support?

The IBAN Validator supports 80+ countries that use the IBAN standard, including all SEPA member states, the UK, Turkey, Saudi Arabia, and many more. The /countries endpoint returns the full list with format specifications for each country.

Can I use these APIs in client-side JavaScript?

Yes. All endpoints support CORS, so you can call them directly from browser-based JavaScript applications. For production use, we recommend proxying requests through your backend to protect your API key.

What is the average response time?

All APIs are built on Cloudflare Workers and deployed to 300+ edge locations worldwide. Average response times are under 100ms globally, with most requests completing in 20-50ms from nearby regions.

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