PostCode Check

Validate and normalize postal codes for 252 countries and territories over MCP and REST. Tools: validate_postcode and list_countries. Format check only — it does not verify that an address exists or is deliverable. Free tier 2,000 calls/month; Basic $9/month for 50,000; Pro $29/month for 500,000.

View on workers.dev

Hosted MCP Server

npx add-mcp 'https://postcodecheck.mike-tusa.workers.dev/mcp'

Installs into Claude Code, Codex, Cursor and more

Documentation

PostCode Check

Check whether a postal code has the right format for its country and get it back in its standard form (for example ec1y8sy → EC1Y 8SY). Covers 252 countries and territories, 182 of which use postal codes. This is a format check: valid means the code has the right shape for the country. It does not confirm that the code is assigned, exists or is deliverable.

JSON API

curl -s 'https://postcodecheck.mike-tusa.workers.dev/v1/validate?country=GB&code=ec1y8sy'
curl -s -X POST https://postcodecheck.mike-tusa.workers.dev/v1/batch -H 'content-type: application/json' \
  -d '{"country":"US","codes":["95014","9501",{"country":"NL","code":"1234ab"}]}'

Routes: GET|POST /v1/validate, GET /v1/countries, POST /v1/batch (up to 100 codes). No key needed today: about 60 requests per minute per IP. OpenAPI 3.1 spec

Plans (a batch counts one call per code): Free $0/mo · 2,000 calls/mo; BASIC $9/mo · 50,000 calls/mo; PRO $29/mo · 500,000 calls/mo. No key: free and anonymous with a per-minute limit per IP. BASIC license keys (PCCR-…) go in Authorization: Bearer <key> or X-API-Key. Get BASIC: https://buy.polar.sh/polar\_cl\_vxapQmele1ma7rDI0te4mqOof1nuv3slVMVEh0zKs7Y PRO license keys (PCCP-…) work the same way. Get PRO: https://buy.polar.sh/polar\_cl\_tgmmwAqsFpnS3lq9bDcz1nFdOnfwcKuY8x2D12T1yc5

For AI agents

PostCode Check is also a remote Model Context Protocol (MCP) server with two read-only tools: validate_postcode and list_countries. Works with AI agents and assistants that can call an MCP server or a JSON API, for example Muse, Claude, ChatGPT or Cursor (descriptive only). Most MCP clients accept this config; some use a different format (for example, VS Code uses a servers key).

{ "mcpServers": { "postcodecheck": { "type": "http", "url": "https://postcodecheck.mike-tusa.workers.dev/mcp" } } }

Machine-readable docs: llms.txt · OpenAPI 3.1 spec · MCP server card.