@postio/core

@postio/core

Runtime-agnostic typed client for Postio — the UK validation API for addresses, emails and phone numbers.

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Works in Node 20+, modern browsers, Cloudflare Workers, Deno, and Bun. Uses the platform's native fetch. Returns the API envelope unchanged so you can hand it straight to your own UI or storage layer.

Install

npm install @postio/core

Use

import { Postio } from "@postio/core";

const postio = new Postio({ apiKey: process.env.POSTIO_API_KEY! });

const search = await postio.address.search("57 wimpole");
// { success: true, results: [{ udprn, suggestion }, …], meta: { requestId, … } }

const full = await postio.address.udprn(search.results[0]!.udprn);
const byPostcode = await postio.address.postcode("W1G 8YW");

const email = await postio.email.validate("[e-mail]");
const phone = await postio.phone.validate("[phone]");

// Free key/health probe — useful as an input-focus warm-up.
await postio.connect();

Options

new Postio({
  apiKey: "pk_…",
  baseUrl: "https://api.postio.co.uk/v1", // default
  timeoutMs: 10_000,                       // default
  fetch: customFetch,                      // override (e.g. tests, proxy)
  headers: { "x-correlation-id": "…" },    // merged into every request
});

Per-request you can pass an AbortSignal:

const ctrl = new AbortController();
const p = postio.address.search("brid", { signal: ctrl.signal });
ctrl.abort(); // throws PostioError with code: "request_aborted"

Errors

Anything non-2xx, network failure, abort, or parse error throws a PostioError. The original API envelope is attached when the server returned one.

import { Postio, PostioError } from "@postio/core";

try {
  await postio.address.udprn(99999999);
} catch (err) {
  if (err instanceof PostioError) {
    err.status;     // 404
    err.code;       // "udprn_not_found"
    err.requestId;  // server-side correlation id
    err.envelope;   // raw { success: false, error, results: [], meta }
  }
}

PostioError.code for transport-level failures: request_timeout, request_aborted, network_error, parse_error, unexpected_content_type.

Types

Every method returns the envelope shape from the OpenAPI spec — { success, results, meta }. Re-exported from @postio/api-types:

import type { Address, EmailResult, PhoneResult, AddressSearchResult } from "@postio/core";

Build

pnpm install
pnpm build

License

MIT.