Leap Year Checker API: Complete Developer Guide

Need to check if a year is a leap year in your application? This guide covers everything about leap year checking via API, including the rules for leap years, calendar information, and implementation examples in multiple programming languages.

What is a Leap Year?

A leap year is a year with 366 days instead of 365, containing an extra day (February 29). Leap years exist to keep our calendar synchronized with the Earth's orbit around the Sun, which takes approximately 365.25 days.

Recent leap years: 2020, 2024, 2028, 2032...

Leap Year Rules

The Gregorian calendar rules for leap years:

Divisible by 4

A year is a leap year if it's divisible by 4. Example: 2024 / 4 = 506

Century Exception

Years divisible by 100 are NOT leap years, unless...

400 Year Rule

Years divisible by 400 ARE leap years. So 2000 was a leap year, but 1900 was not.

Using the Leap Year API

TinyFn provides a simple endpoint to check leap years:

GET https://api.tinyfn.io/v1/time/is-leap-year?year=2024
Headers: X-API-Key: your-api-key

{
  "year": 2024,
  "is_leap_year": true,
  "days_in_year": 366,
  "days_in_february": 29,
  "next_leap_year": 2028,
  "previous_leap_year": 2020
}

Parameters

Code Examples

JavaScript / Node.js

const response = await fetch(
  'https://api.tinyfn.io/v1/time/is-leap-year?year=2024',
  { headers: { 'X-API-Key': 'your-api-key' } }
);
const result = await response.json();
console.log(result.is_leap_year); // true
console.log(`February has ${result.days_in_february} days`);

Python

import requests

response = requests.get(
    'https://api.tinyfn.io/v1/time/is-leap-year',
    params={'year': 2024},
    headers={'X-API-Key': 'your-api-key'}
)
result = response.json()
print(result['is_leap_year'])  # True
print(f"February has {result['days_in_february']} days")

cURL

curl "https://api.tinyfn.io/v1/time/is-leap-year?year=2024" \
  -H "X-API-Key: your-api-key"

Common Use Cases

• Date Validation: Check if Feb 29 is valid for a given year
• Calendar Apps: Display correct number of days in February
• Age Calculation: Handle Feb 29 birthdays correctly
• Financial Apps: Calculate day counts accurately for interest
• Scheduling: Plan events considering leap years

Best Practices

1. Don't hardcode: Use the API for accurate results, don't just check % 4
2. Handle Feb 29: Decide how to handle Feb 29 birthdays in non-leap years
3. Test centuries: Verify your code handles 1900 and 2000 correctly
4. Consider historical dates: Julian calendar had different rules before 1582