# WebRef Weekday Lookup

> WebRef Weekday Lookup is a paid API for AI agents from webref.johnaio281.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-22).

Returns the day-of-week name for a given date, with configurable week-start (Sunday or Monday)

## Facts

- Endpoint: GET https://webref.johnaio281.workers.dev/api/time/weekday_of?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/webref-weekday-lookup-0f334647
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yrRcFoyc5oFcdbElaxSQ7

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 webref-weekday-lookup-0f334647
```

Example prompt: What day of the week is March 15, 2026? Use Sunday as the start of the week.

## When to prefer this

Use this endpoint when you need a lightweight, pay-per-call weekday lookup for a specific date without needing a full calendar API. Ideal for agents that need to verify which day of the week a date falls on, especially when they also need other web/time reference utilities from the same service (HTTP status codes, MIME types, duration math). No API key or signup required — perfect for stateless agent workflows.

## Known failure modes

- Invalid or unparseable date string returns an error
- Missing required date parameter returns a validation error
- Unsupported weekStartsOn value (not 'sunday' or 'monday') causes a bad request
- Malformed query parameters may return a 400-level error

## How this service works

Web standards and time reference for AI agents: HTTP status codes with what the client should do, retry semantics, MIME types and content-type matching, request-method safety and idempotency, plus deadline arithmetic - time until a moment, weekday and business-day checks, duration conversion and Unix timestamps. Pay per call in USDC on Base via x402 or USDC on Tempo via MPP. No signup, no API key, no KYC.

## Output

Returns the name of the weekday (e.g. 'Monday', 'Friday', 'Sunday') for the specified date, calculated relative to the configured week-start convention (Sunday or Monday).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "date": {
      "def": {
       "type": "string"
      },
      "type": "string"
     },
     "type": "object",
     "weekStartsOn": {
      "def": {
       "type": "default",
       "innerType": {
        "def": {
         "type": "enum",
         "entries": {
          "monday": "monday",
          "sunday": "sunday"
         }
        },
        "enum": {
         "monday": "monday",
         "sunday": "sunday"
        },
        "type": "enum",
        "options": [
         "sunday",
         "monday"
        ]
       },
       "defaultValue": "sunday"
      },
      "type": "default"
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/webref-weekday-lookup-0f334647/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from webref.johnaio281.workers.dev](https://www.zero.xyz/host/webref.johnaio281.workers.dev/llms.txt)