ISO date difference

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

Whole days from start to end as a canonical integer string (end - start).

Use when you need to: iso date difference · days between dates · date minus date.

Supported

• iso date difference
• days between dates
• date minus date

Not supported

• business days
• timezones
• hours
• locale

Behavior

• Both dates are strict YYYY-MM-DD as iso-date-add.
• days is the signed canonical integer string of (end - start) in civil days.
• Same date -> "0". end before start is negative.

Input

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

Output

• days (string, required)

Limits

• year min: 1
• year max: 9999

Example

Request input:

{
  "start": "2026-09-10",
  "end": "2026-09-11"
}

Response:

{
  "result": {
    "days": "1"
  }
}

How to call it

MCP

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

{
  "id": "iso-date-difference",
  "version": "1.0.0",
  "input": {
    "start": "2026-09-10",
    "end": "2026-09-11"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/iso-date-difference/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"start":"2026-09-10","end":"2026-09-11"}'

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

CLI

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

Get the client at /clients/cli/.

Related tools

• ISO date age: Compute the calendar-aware elapsed years, months, and days between a birth date and an as-of date.
• ISO date business days count: Count the business days in an inclusive date range, skipping caller-supplied weekend weekdays and holidays.
• ISO date range intersect: Compute the intersection of two inclusive [start, end] date ranges.
• ISO date range list: Enumerate the dates in an inclusive [start, end] range stepped by a whole number of days.
• ISO date weekday occurrences in range: List every date within an inclusive date range that falls on a given ISO weekday.
• ISO date add: Add a signed whole-day delta to a strict YYYY-MM-DD calendar date.