UK Companies House

Overview

The Companies House API serves the UK company registry — search, filing history, and officers. Auth is an API key (Basic auth; missing auth returns 401, verified).

Quick Start

Search companies (replace YOUR_KEY):

curl "https://api.company-information.service.gov.uk/search/companies?q=google" \
  -u "YOUR_KEY:"

{
  "items": [
    {
      "company_number": "03977902",
      "title": "GOOGLE UK LIMITED",
      "company_status": "active",
      "company_type": "ltd",
      "address_snippet": "6 Pancras Square, London"
    }
  ]
}

Authentication

• Register at developer.company-information.service.gov.uk → free API key.
• Send it as HTTP Basic with the key as the username (password empty); missing → 401 (verified).

Rate Limits & Notes

• Free tier: 600 requests/5 minutes (check the docs) — generous.
• Endpoints: /search/companies, /company/{number}, /company/{number}/filing-history, /company/{number}/officers.

FAQ

Is Companies House free? Yes — a free key with generous rate limits.

How do I get a key? developer.company-information.service.gov.uk → register.

What’s the auth style? Basic auth, key as username (verified).