ISO date add years

iso-date-add-years · version 1.0.0 · Dates & times (UTC, ISO 8601) · free, no key needed

Add a signed whole-year delta to a YYYY-MM-DD date, clamping the day if 29 February has no match.

Use when you need to: iso date add years · add calendar years to a date · shift date by years.

Supported

• iso date add years
• add calendar years to a date
• shift date by years

Not supported

• add days
• add months
• add seconds
• time zones
• fiscal years
• datetime with time

Behavior

• date is a proleptic Gregorian UTC calendar date YYYY-MM-DD with years 0001-9999.
• years is a canonical integer string with at most 5 digits excluding sign; -0 is accepted as 0.
• The month and day-of-month are kept unchanged except that 29 February is clamped to 28 February when the target year is not a leap year.
• The result year must stay in 0001-9999, or the call is rejected.
• Output date is zero-padded YYYY-MM-DD.

Input

• date (string, required): min length 10; max length 10; pattern ^\d{4}-\d{2}-\d{2}$
• years (string, required): max length 6; pattern ^-?(0|[1-9][0-9]*)$

Output

• date (string, required): min length 10; max length 10

Limits

• year min: 1
• year max: 9999
• max years digits: 5

Example

Request input:

{
  "date": "2026-09-15",
  "years": "1"
}

Response:

{
  "result": {
    "date": "2027-09-15"
  }
}

How to call it

MCP

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

{
  "id": "iso-date-add-years",
  "version": "1.0.0",
  "input": {
    "date": "2026-09-15",
    "years": "1"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/iso-date-add-years/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"date":"2026-09-15","years":"1"}'

The machine-readable contract is at /v1/tools/iso-date-add-years/versions/1.0.0.

CLI

node cli.mjs run iso-date-add-years 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• ISO date add months: Add a signed month count to a YYYY-MM-DD date, clamping the day to the target month.
• ISO date-time add seconds: Add a signed whole-second delta to a strict UTC ISO-8601 datetime.
• ISO date add: Add a signed whole-day delta to a strict YYYY-MM-DD calendar date.
• ISO date age: Compute the calendar-aware elapsed years, months, and days between a birth date and an as-of date.
• ISO date business day add: Add a signed count of business days to a date, skipping caller-supplied weekend weekdays and holidays.
• ISO date days in month: Return the number of calendar days in a given proleptic Gregorian year and month.