# SiteCheck Postcode Lookup

> SiteCheck Postcode Lookup is a paid API for AI agents from api.sitecheck-api.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-23).

Resolves a postcode or ZIP code to geographic and administrative details including coordinates, region, district, and constituency

## Facts

- Endpoint: GET https://api.sitecheck-api.workers.dev/api/postcode?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-postcode-lookup-1d8ee564
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fULXXEo5YJbp8CA-zFrS4

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 sitecheck-postcode-lookup-1d8ee564
```

Example prompt: What region, district, and coordinates does the UK postcode SW1A 1AA belong to?

## When to prefer this

Choose this endpoint when you need to resolve a UK postcode (or other country ZIP code) to structured geographic and administrative data including coordinates, region, district, and constituency. It is backed by postcodes.io with OS Crown copyright data, making it authoritative for UK addresses. Prefer it over generic geocoding APIs when administrative boundary data (constituency, district, county) is needed alongside coordinates.

## Known failure modes

- Invalid or malformed postcode returns an error or empty places array
- Unsupported country code may yield no results
- Postcode that no longer exists (retired postcodes) may return empty results
- Missing required query parameters (country or code) returns a validation error
- Network timeout or upstream postcodes.io unavailability

## How this service works

Place names and coordinates for a postcode. GB adds district, ward and constituency (postcodes.io); other countries use Zippopotam.us for ZIP and postal codes. A postcode that does not exist answers 404, not charged.

## Output

A JSON object containing the postcode, an array of matching places each with latitude, longitude, county, region, district, place name, and constituency, plus the country code, lookup timestamp, data source attribution, and a link to postcodes.io.

## 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"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "country",
      "code"
     ],
     "properties": {
      "code": {
       "type": "string",
       "description": "Postcode or ZIP code"
      },
      "country": {
       "type": "string",
       "description": "ISO 3166 alpha-2 code, e.g. GB"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "code": "SW1A 1AA",
  "places": [
   {
    "lat": 51.50101,
    "lon": -0.141563,
    "county": null,
    "region": "London",
    "district": "Westminster",
    "placeName": "St James's",
    "constituency": "Cities of London and Westminster"
   }
  ],
  "source": "postcodes.io (https://api.postcodes.io)",
  "country": "GB",
  "checkedAt": "2026-10-14T04:49:24.511Z",
  "attribution": "Contains OS data © Crown copyright and database right; postcodes.io (Open Government Licence v3.0)"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sitecheck-postcode-lookup-1d8ee564/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.sitecheck-api.workers.dev](https://www.zero.xyz/host/api.sitecheck-api.workers.dev/llms.txt)