What is the easiest way to install Postio?

It depends where your code runs. For a website, the drop-in address-finder widget is a single script tag. For WordPress or WooCommerce, the free plugin needs no code. For a back end, install the SDK for your language. The Integrations directory at postio.co.uk/integrations lists every option with copy-paste install instructions.

Should I load the address widget from the CDN or from npm?

Use the CDN script tag if you have no build step — it is the fastest way onto a plain site or CMS. Install @postio/address-finder (or @postio/react) from npm if you bundle your front end, so it ships with your app and you get types.

Which languages have an official Postio SDK?

Postio publishes official SDKs for JavaScript/Node (@postio/node), Python (postio), Go (postio-go), PHP (postio/postio), Ruby (postio) and .NET (Postio.Sdk). All are open source under the MIT licence.

Do I need an SDK to use the Postio API?

No. Every endpoint is a plain GET request that returns JSON, so any HTTP client works. The SDKs are a convenience — they add typed responses, auth handling and an automatic retry policy.

Build with it

SDKs & libraries

You can call Postio with nothing but an HTTP client, but most people reach for a ready-made install: a server SDK, the drop-in browser widget, an MCP server, or a no-code platform plugin. The Integrations directory is the full, copy-paste index of every one.

Ways to use Postio

There are four routes in, depending on where your code runs. The Integrations directory lists every one with install instructions and a dedicated page each — start there if you are not sure which fits.

Server-side — an official SDK for your language (below), or a plain GET if you prefer no dependency.
In the browser — the drop-in address autocomplete widget, from the CDN or npm. See Browser: CDN or npm.
AI agents — the MCP server.
No code — a WordPress plugin, Zapier, and more platform plugins on the way. Often the fastest install of all.

Server SDKs

Six official, open-source (MIT) clients, each idiomatic to its language and each mirroring the same API. All carry the same retry policy — two retries with exponential backoff and full jitter, on 408, 409, 429, 5xx and network errors.

Language	Package	Install	Guide
JavaScript / Node	@postio/node	npm install @postio/node	Guide
Python	postio	pip install postio	Guide
Go	postio-go	go get github.com/postio-uk/postio-go	Guide
PHP	postio/postio	composer require postio/postio	Guide
Ruby	postio	gem install postio	Guide
.NET	Postio.Sdk	dotnet add package Postio.Sdk	Guide

Each SDK exposes the address, email and phone endpoints with typed results. The linked guide covers install and the exact method names for your language; the package link goes to the registry.

Browser: CDN or npm

For a UK address autocomplete field on a website, use the address-finder widget. There are two ways to load it — pick by whether you have a build step. Either way, use an origin-locked key (see Authentication) since it runs in the browser.

From the CDN (no build step)

One script tag, around 4.2 KB gzipped. Best for a plain site, a CMS, or anywhere you cannot run a bundler:

<script src="https://cdn.postio.co.uk/v1/address-finder.js"></script>

An ES module build (address-finder.esm.js) sits beside it, and an immutable version pin (/v1.1.0/…) is there for when you want to lock the version. The /v1/ URL auto-updates with fixes.

From npm (with a bundler)

If you build your front end, install the package instead — you get types and it bundles with your app:

npm install @postio/address-finder

@postio/address-finder — the widget; -bundled ships its dependencies inlined.
@postio/react — a React component wrapping the same widget.

AI agents (MCP)

The Postio MCP server (@postio/mcp) exposes Postio’s address, email and phone tools to AI agents and MCP-aware hosts. It is listed on the official MCP registry, so most aggregators pick it up automatically. There is also a Claude Skill and Cursor rules for coding agents.

No-code platforms

Often the fastest install — no code at all:

WordPress — a free plugin adding UK address autocomplete to WooCommerce and every major form builder. Live on WordPress.org.
Zapier — validate in your automations (beta, invite-only).
More platforms — Shopify and Magento are on the way; the directory tracks status.

API tooling

OpenAPI spec — /openapi.json (also @postio/openapi on npm) for codegen and API clients.
@postio/cli — validate from the command line.
@postio/postman-collection — a ready-made Postman collection.

FAQ

What is the easiest way to install Postio?: It depends where your code runs. For a website, the drop-in address-finder widget is a single script tag. For WordPress or WooCommerce, the free plugin needs no code. For a back end, install the SDK for your language. The Integrations directory at postio.co.uk/integrations lists every option with copy-paste install instructions.
Should I load the address widget from the CDN or from npm?: Use the CDN script tag if you have no build step — it is the fastest way onto a plain site or CMS. Install @postio/address-finder (or @postio/react) from npm if you bundle your front end, so it ships with your app and you get types.
Which languages have an official Postio SDK?: Postio publishes official SDKs for JavaScript/Node (@postio/node), Python (postio), Go (postio-go), PHP (postio/postio), Ruby (postio) and .NET (Postio.Sdk). All are open source under the MIT licence.
Do I need an SDK to use the Postio API?: No. Every endpoint is a plain GET request that returns JSON, so any HTTP client works. The SDKs are a convenience — they add typed responses, auth handling and an automatic retry policy.