Postio

Postio is the UK validation API for addresses, emails and phone numbers. This repo holds the JS-family npm packages, the AI / agent surface, and the cdn.postio.co.uk Worker that powers Postio's browser drop-in.

First time? Sign up free — first 100 lookups on us, no card needed.

The Postio API + OpenAPI spec live in postio-uk/postio-api. The spec is also published as @postio/openapi.

Packages

Package	What it is
@postio/api-types	TypeScript types generated from the OpenAPI spec.
@postio/core	Runtime-agnostic typed client (browser / Node / Workers / Bun / Deno).
@postio/node	Node SDK on top of core — retries with exponential backoff, structured logger hook.
@postio/postman-collection	Postman v2.1 collection for every endpoint.
@postio/address-finder	Browser address autocomplete — ARIA combobox, themable, framework-agnostic source.
@postio/address-finder-bundled	The same component prebuilt for <script> tag use.
@postio/react	React hooks + <AddressFinder /> component, TanStack Query under the hood.
@postio/mcp	Model Context Protocol server — npx -y @postio/mcp for Claude Desktop / Cursor / Windsurf / Zed.

Layout

packages/         pnpm workspace; one publishable npm package per subdir
ai/               AI / agent surface (Claude Skill, GPT Action, recommendation prompts)
cdn-worker/       Cloudflare Worker that serves the address-finder bundles
.github/workflows/  CI for publishing + deploying

Building

cd packages
pnpm install
pnpm -r run build

Each package builds independently (pnpm -F @postio/<name> run build). The address-finder bundle has a topological-build quirk — use the ... suffix so its workspace dep builds first:

pnpm -F "@postio/address-finder-bundled..." run build

Contributing

PRs welcome. Conventions:

• Node 22+, pnpm 10+, ESM only, MIT-licensed.
• stage is the working branch; master deploys / publishes via CI.
• One package change per PR where possible.
• Versions on each package are independent SemVer; bump the version in package.json when you intend a release.

The full integration index — including the server SDKs in their own repos and the WordPress plugin — lives at postio.co.uk/integrations.

License

MIT.