Grand Public API

The Grand Public API gives partner engineers programmatic access to official company records for the United Kingdom (GB) and Ireland (IE). Search for a company by name, then retrieve its registered legal name, registration number, and current trading status — sourced from the same registry data that powers Grand.

It's a small, predictable REST API: three endpoints, JSON over HTTPS, OAuth 2.0 bearer authentication. If you've integrated with any modern API, you'll be productive in minutes.

What you can do

Find companies by name within a jurisdiction and get their registration numbers, status, and address. Retrieve the registered legal name, registration number, and trading status for any company in Grand's network.

Base URL

All requests go to a single host, and every endpoint is prefixed with /v1:

https://public-api.heygrand.com

API conventions

A few things hold true across every endpoint:

Convention	Detail
Transport	HTTPS only. Plain HTTP is not supported.
Format	Requests and responses use `application/json`.
Authentication	OAuth 2.0 bearer token in the `Authorization` header (except the token endpoint itself).
Versioning	The major version is in the path (`/v1`). See Versioning.
Jurisdictions	Supplied as an ISO 3166-1 alpha-2 code. GB and IE are supported — see Jurisdictions.

The API is read-only. Every endpoint either returns data or authenticates you — nothing you call will modify state, so requests are always safe to retry.

Before you start

You'll need a client_id and client_secret, issued by Grand. If you don't have them yet, contact your account manager or email support@heygrand.com.

Next steps

Go from credentials to your first profile in under five minutes. Learn the OAuth 2.0 flow and how to manage token expiry. Explore every endpoint, parameter, and response schema.

Quickstart