# Find old and invalid UK postcodes in a customer list

**Use case:** 

Paste a postcode column from your CRM or spreadsheet and see which entries are active, terminated (no longer used, with end date), not found, badly formatted, duplicated or in Northern Ireland. Each row keeps its input position and a plain reason. The example mixes a valid, an old, an unknown, a typo, a BT and a repeated postcode. Useful for CRM cleaning and address data quality.

## Input

```json
{
  "postcodes": [
    "sw1a2aa",
    "AB1 0AA",
    "ZZ1 1ZZ",
    "not a postcode",
    "BT1 5GS",
    "SW1A 2AA",
    "EH99 1SP"
  ],
  "includeTerminated": true
}
```

## Output

```json
{
  "inputIndex": {
    "label": "#",
    "format": "integer"
  },
  "input": {
    "label": "Input",
    "format": "string"
  },
  "postcode": {
    "label": "Postcode",
    "format": "string"
  },
  "status": {
    "label": "Status",
    "format": "string"
  },
  "statusReason": {
    "label": "Reason",
    "format": "string"
  },
  "errorCode": {
    "label": "Error code",
    "format": "string"
  },
  "duplicateOfIndex": {
    "label": "Duplicate of #",
    "format": "integer"
  },
  "terminatedOn": {
    "label": "Terminated",
    "format": "string"
  }
}
```

## How it works

### 1. Sign up on Apify or log in

The UK Postcode Lookup Actor is ready to run with the inputs already set for "Find old and invalid UK postcodes in a customer list". [Sign up or log in](https://console.apify.com/create-task-from-example/V6Ag2k7Z6BdlePYVi) and you'll land in Apify Console with a copy of this exact task.

### 2. Start the "Find old and invalid UK postcodes in a customer list" task

The UK Postcode Lookup Actor will start running based on the input automatically. You can also change all the input fields, like postcodes and check terminated postcodes, to match your specific use case.

### 3. Receive the "Find old and invalid UK postcodes in a customer list" output

Monitor the progress in real time. You will be notified as soon as your dataset is complete and ready for review. Each result includes data such as #, input, postcode, and more.

### 4. Integrate into your workflow

The final output is delivered in JSON, CSV, or Excel format, ready to be plugged into your workflow. You can also [run the "Find old and invalid UK postcodes in a customer list" task via API](https://apify.com/cliqtomedia/gb-postcode-lookup.md).

## About this Actor

This example demonstrates how to use [UK Postcode Lookup](https://apify.com/cliqtomedia/gb-postcode-lookup.md) with a specific input configuration. Visit the [Actor detail page](https://apify.com/cliqtomedia/gb-postcode-lookup.md) to learn more, explore other use cases, and run it yourself.


## How to integrate an Actor?

This Task's input is already configured above. Use it as-is rather than inventing a new one.

Do not guess an integration path. Every one of them is in the agent quickstart at https://apify.com/agents.md: the Apify MCP server, Agent Skills with the Apify CLI, the JavaScript and Python clients, the REST API, and the account-free path for an agent with no human to sign in. It also carries the rule on stating cost before the first paid run.

For full API examples (JavaScript, Python, CLI, MCP, OpenAPI), see this Task's Actor page: https://apify.com/cliqtomedia/gb-postcode-lookup.md

Each client library has reference documentation the quickstart does not restate: [JavaScript/TypeScript](https://docs.apify.com/api/client/js/docs.md) (`npm install apify-client`) and [Python](https://docs.apify.com/api/client/python/docs.md) (`pip install apify-client`).