ISO date range overlap

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

Test whether two inclusive [start, end] date ranges share at least one day.

Use when you need to: iso date range overlap · do two date ranges overlap · date range collision check.

Supported

• iso date range overlap
• do two date ranges overlap
• date range collision check

Not supported

• open ranges
• timezones
• datetime ranges

Behavior

• a and b are each an inclusive [start, end] YYYY-MM-DD date range with year 0001-9999; start must not be after end in either.
• overlap is true if the two closed ranges share at least one calendar day (a.start <= b.end && b.start <= a.end), false otherwise.

Input

• a (object, required)
• b (object, required)

Output

• overlap (boolean, required)

Limits

• year min: 1
• year max: 9999

Example

Request input:

{
  "a": {
    "start": "2026-01-01",
    "end": "2026-01-10"
  },
  "b": {
    "start": "2026-01-05",
    "end": "2026-01-20"
  }
}

Response:

{
  "result": {
    "overlap": true
  }
}

How to call it

MCP

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

{
  "id": "iso-date-range-overlap",
  "version": "1.0.0",
  "input": {
    "a": {
      "start": "2026-01-01",
      "end": "2026-01-10"
    },
    "b": {
      "start": "2026-01-05",
      "end": "2026-01-20"
    }
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/iso-date-range-overlap/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"a":{"start":"2026-01-01","end":"2026-01-10"},"b":{"start":"2026-01-05","end":"2026-01-20"}}'

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

CLI

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

Get the client at /clients/cli/.

Related tools

• ISO date range intersect: Compute the intersection of two inclusive [start, end] date ranges.
• ISO date range contains: Test whether an inclusive [start, end] date range contains a given date.
• ISO date range list: Enumerate the dates in an inclusive [start, end] range stepped by a whole number of days.
• ISO date range union: Merge overlapping or day-adjacent inclusive [start, end] date ranges into the fewest equivalent ranges.
• ISO date weekday occurrences in range: List every date within an inclusive date range that falls on a given ISO weekday.
• ISO date business days count: Count the business days in an inclusive date range, skipping caller-supplied weekend weekdays and holidays.