I built a UK postcode validator for Laravel.

Designed to work with Laravel's form validation, but also works manually as a facade pattern.

Features:

• Checks postcode against an external API
• Uses ONS and Ordnance Survey postcode data
• Determines postcode country
• Supports England, Wales, Scotland and Northern Ireland
• Supports the Isle of Man and the Channel Islands
• Falls back to regex validation if the external API is unavailable
• Allows countries or areas to be excluded

Details here:

https://github.com/chisnall/postcode

Works with Laravel 9 to 12.

Here: https://github.com/chisnall/squiz