UK Address Autocomplete & Postcode Lookup for Forms & WooCommerce

Postio is a UK address, email, and phone validation API. This plugin drops UK address autocomplete onto your existing forms — automatically — so customers fill billing, shipping, and contact addresses in two keystrokes instead of twenty.

Automatic, where your builder has an address field

Paste your key and these wire themselves. No classes, no snippets, no per-form setup:

• WooCommerce — both Block Checkout (the new Cart / Checkout block) and the classic shortcode checkout, plus My Account → Addresses.
• Gravity Forms — every Address field on every form.
• Fluent Forms — Address field, multi-form-safe.
• Forminator — Address field with all sub-inputs.
• WPForms — Address field across every form. (The Address field is part of WPForms Pro; on WPForms Lite, use the two-minute route below.)

Two-minute setup, everywhere else

Some builders have no address field at all — there’s nothing for us to detect, because there’s nothing there. You tell us which of your fields are which by adding a class to each one, and it works exactly the same from then on:

• Contact Form 7
• Ninja Forms
• Elementor Forms (part of Elementor Pro)

You don’t have to go hunting for the classes. Settings → Postio detects which of these you have installed and prints the exact snippet for your builder on the screen, ready to copy.

Anything else

Custom mappings at Settings → Postio bind any search box to any set of output fields by CSS selector. That covers page builders, bespoke themes and hand-written forms — anything that renders ordinary HTML inputs.

Plus a block (Postio Address Finder) that drops onto any page in the block editor for one-off address pickers.

Why Postio

• Royal Mail PAF + Ordnance Survey — the same dataset every UK address vendor uses, served from edge workers in two regions for sub-50ms typeahead.
• No accuracy compromise — you get the same dataset whether you spend £20 a month or £2,000.
• No setup tax — builders with a real address field are wired the moment you save your key. The rest take one class per field, and the plugin shows you exactly which ones on the settings screen.
• Free plugin, metered API — the plugin itself costs nothing. You pay only for the API calls your customers make. UK pricing, UK support, [postio] is a trading name of Onno Group Limited.

How it works

When the customer types into an address field on any of the supported forms, the plugin shows ranked suggestions backed by the live Postio API. On selection, every other address sub-field on the form (Town, Postcode, etc.) auto-fills.

The autocomplete script ships with the plugin — nothing is loaded from a remote CDN. It is ~4.2 KB gzipped and is only enqueued on pages that actually have a relevant form, and only when an API key is configured.

External services

This plugin connects to the Postio API to look up UK addresses. The service is required — address autocomplete cannot work without it, because the address data lives on Postio’s servers, not in your WordPress install.

• Service: Postio validation API — https://postio.co.uk (API endpoint https://api.postio.co.uk), operated by Onno Group Limited, registered in England & Wales, company no. 08622799. Registered office: Suite 22 Trym Lodge, 1 Henbury Road, Westbury-On-Trym, Bristol BS9 3HQ.
• What it does: returns matching UK addresses for a postcode or partial address, from Royal Mail PAF and Ordnance Survey data.
• What is sent: the postcode or address text typed into a wired field, your API key, and the site’s origin URL. Nothing else. No names, no email addresses, no order data, no personal data beyond the address text itself.
• When it is sent: only when a visitor is actively typing into an address field the plugin is attached to, or when you press Test connection on the settings screen. Nothing is sent until you have entered an API key, and nothing is sent in the background — there is no analytics, no usage tracking and no phoning home.
• Terms of service: https://postio.co.uk/terms
• Privacy policy: https://postio.co.uk/privacy

No executable code is downloaded from anywhere. The autocomplete script is bundled in the plugin at assets/address-finder.js.