# ISO date business day add

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

Add a signed count of business days to a date, skipping caller-supplied weekend weekdays and holidays.

**Use when you need to: iso date business day add · add working days to date · skip weekends and holidays.**

## Supported

- iso date business day add
- add working days to date
- skip weekends and holidays

## Not supported

- built-in national holiday calendars
- timezones
- half-day rules
- fractional business days

## Behavior

- date is a strict YYYY-MM-DD proleptic Gregorian UTC calendar date with year 0001-9999.
- days is a canonical signed integer string with absolute value at most 100000.
- weekend_days is an array of ISO weekday integers 1-7, unique, at most 6 entries. holidays is an array of unique YYYY-MM-DD dates, at most 366 entries.
- The starting date itself is never counted as a step. days=0 returns date unchanged, even if date is a weekend or holiday.
- A positive days steps forward one calendar day at a time, skipping weekend_days and holidays, until days business days have been counted. Negative days steps backward the same way.
- The call is rejected if a step would move outside year 0001-9999.

## Input

- `date` (string, required): min length 10; max length 10; pattern `^\d{4}-\d{2}-\d{2}$`
- `days` (string, required): max length 8; pattern `^-?(0|[1-9][0-9]*)$`
- `weekend_days` (array of integer, required): max items 6; each min 1; each max 7
- `holidays` (array of string, required): max items 366; each min length 10; each max length 10

## Output

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

## Limits

- year min: 1
- year max: 9999
- max abs days: 100000
- max weekend days: 6
- max holidays: 366

## Example

Request input:

```json
{
  "date": "2026-09-18",
  "days": "1",
  "weekend_days": [
    6,
    7
  ],
  "holidays": []
}
```

Response:

```json
{
  "result": {
    "date": "2026-09-21"
  }
}
```

## How to call it

### MCP

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

```json
{
  "id": "iso-date-business-day-add",
  "version": "1.0.0",
  "input": {
    "date": "2026-09-18",
    "days": "1",
    "weekend_days": [
      6,
      7
    ],
    "holidays": []
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/iso-date-business-day-add/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"date":"2026-09-18","days":"1","weekend_days":[6,7],"holidays":[]}'
```

The machine-readable contract is at [/v1/tools/iso-date-business-day-add/versions/1.0.0](/v1/tools/iso-date-business-day-add/versions/1.0.0).

### CLI

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

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

## Related tools

- [ISO date is business day](/tools/iso-date-is-business-day): Test whether a date is a business day given caller-supplied weekend weekdays and holiday dates.
- [ISO date add](/tools/iso-date-add): Add a signed whole-day delta to a strict YYYY-MM-DD calendar date.
- [ISO date business days count](/tools/iso-date-business-days-count): Count the business days in an inclusive date range, skipping caller-supplied weekend weekdays and holidays.
- [ISO date add months](/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 add years](/tools/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 from day of year](/tools/iso-date-from-day-of-year): Convert a calendar year and ordinal day number (1-366) to a YYYY-MM-DD date.