# ISO Week Number

> ISO Week Number is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-16).

Returns the ISO week number (and year context) for a given date, useful for weekly reporting buckets and standup cadence keys.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/iso-week
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/iso-week-number-aa8696f1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__YOIcoTkNltJ4whRxQmUQ

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability iso-week-number-aa8696f1 -d '<json body>'
```

Example prompt: What ISO week number does March 15, 2026 fall into? I need it for my weekly reporting buckets.

## When to prefer this

Choose this endpoint when you need a deterministic, no-key, pay-per-call ISO week number lookup without any subscription or account setup. It is ideal for agents that need weekly bucket keys or standup cadence identifiers for arbitrary dates, especially in automated pipelines where reliability and zero-config access matter. Prefer this over building custom logic when correctness around year-boundary edge cases is important.

## Known failure modes

- Invalid or malformed date string returns a structured validation error (not billed)
- Missing date field returns a validation error
- Dates near year boundaries may return a week year different from the calendar year (expected ISO 8601 behavior)
- Network or payment failure prevents the call from completing

## How this service works

ISO week number. Call for weekly reporting buckets and standup cadence keys. Returns ISO week number (and year context) for a date. $0.001 USDC per successful call via x402 on Base—deterministic first-party JSON, no API key, no subscription, and nothing is billed on structured validation errors.

## Output

A JSON object containing the ISO week number for the provided date, along with the ISO week year context (since ISO weeks can span year boundaries), returned as deterministic first-party JSON.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "date": {
   "type": "string",
   "format": "date-time",
   "description": "ISO-8601 date or timestamp (e.g. 2026-08-04 or 2026-08-04T12:00:00Z)."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "week": 32,
  "year": 2026,
  "schema": "delx/iso-week/v1",
  "weekday": 2
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/iso-week-number-aa8696f1/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)