ISO date is leap year

iso-date-is-leap-year · version 1.0.0 · Dates & times (UTC, ISO 8601) · free, no key needed

Test whether a proleptic Gregorian calendar year is a leap year.

Use when you need to: iso date is leap year · leap year check · is year a leap year.

Supported

• iso date is leap year
• leap year check
• is year a leap year

Not supported

• Julian calendar
• lunar calendars
• timezones

Behavior

• year is a JSON integer from 1 to 9999.
• Leap year rule: year % 4 == 0 && (year % 100 != 0 || year % 400 == 0). For example 2000 and 2024 are leap years; 1900 and 2023 are not.

Input

• year (integer, required): min 1; max 9999

Output

• leap (boolean, required)

Limits

• year min: 1
• year max: 9999

Example

Request input:

{
  "year": 2024
}

Response:

{
  "result": {
    "leap": true
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "iso-date-is-leap-year",
  "version": "1.0.0",
  "input": {
    "year": 2024
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/iso-date-is-leap-year/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"year":2024}'

The machine-readable contract is at /v1/tools/iso-date-is-leap-year/versions/1.0.0.

CLI

node cli.mjs run iso-date-is-leap-year 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• ISO date is business day: Test whether a date is a business day given caller-supplied weekend weekdays and holiday dates.
• ISO date range contains: Test whether an inclusive [start, end] date range contains a given date.
• ISO date week count in year: Return the number of ISO-8601 weeks (52 or 53) in an ISO week-numbering year.
• ISO date add years: Add a signed whole-year delta to a YYYY-MM-DD date, clamping the day if 29 February has no match.
• ISO date day of year: Return the ordinal day number (1-366) of a YYYY-MM-DD date within its calendar year.
• ISO date days in month: Return the number of calendar days in a given proleptic Gregorian year and month.