# ISO date next weekday

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

Return the next date on or after a given date that falls on a specified ISO weekday.

**Use when you need to: iso date next weekday · next monday after date · upcoming weekday.**

## Supported

- iso date next weekday
- next monday after date
- upcoming weekday

## Not supported

- timezones
- locale weekday names
- business day skip

## Behavior

- date is a strict YYYY-MM-DD proleptic Gregorian UTC calendar date with year 0001-9999.
- weekday is a JSON integer 1-7 with Monday=1 .. Sunday=7.
- inclusive is an optional boolean, default false. When true and date already falls on weekday, the result is date itself.
- Otherwise the result is the earliest date strictly after date whose ISO weekday equals weekday (at most 7 days later).
- The call is rejected if the result would fall outside year 0001-9999.

## Input

- `date` (string, required): min length 10; max length 10; pattern `^\d{4}-\d{2}-\d{2}$`
- `weekday` (integer, required): min 1; max 7
- `inclusive` (boolean, optional)

## Output

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

## Limits

- year min: 1
- year max: 9999
- max days forward: 7

## Example

Request input:

```json
{
  "date": "2026-09-15",
  "weekday": 5
}
```

Response:

```json
{
  "result": {
    "date": "2026-09-18"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "iso-date-next-weekday",
  "version": "1.0.0",
  "input": {
    "date": "2026-09-15",
    "weekday": 5
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/iso-date-next-weekday/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"date":"2026-09-15","weekday":5}'
```

The machine-readable contract is at [/v1/tools/iso-date-next-weekday/versions/1.0.0](/v1/tools/iso-date-next-weekday/versions/1.0.0).

### CLI

```sh
node cli.mjs run iso-date-next-weekday 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [ISO date nth weekday of month](/tools/iso-date-nth-weekday-of-month): Return the date of the nth occurrence of an ISO weekday within a calendar month.
- [ISO date previous weekday](/tools/iso-date-previous-weekday): Return the most recent date on or before a given date that falls on a specified ISO weekday.
- [ISO date weekday occurrences in range](/tools/iso-date-weekday-occurrences-in-range): List every date within an inclusive date range that falls on a given ISO weekday.
- [ISO date last weekday of month](/tools/iso-date-last-weekday-of-month): Return the date of the last occurrence of an ISO weekday within a calendar month.
- [ISO date to week](/tools/iso-date-to-week): Convert a YYYY-MM-DD calendar date to an ISO-8601 week date.
- [ISO date week bounds](/tools/iso-date-week-bounds): Return the Monday and Sunday of the ISO-8601 week that contains a calendar date.