UK Companies House API: free company registry data guide

What is the Companies House API?

The Companies House API is the official free REST interface to the UK company register, covering more than 5 million registered companies, according to Companies House statistics. One API key — issued free on registration — unlocks company profiles, filing history, directors, and beneficial owners. In our data, it is the single richest no-cost company registry in Europe: unlike most EU registers, it exposes ownership, not just existence. The three record types that matter for company research:

• Company profile: legal name, status, incorporation date, registered address, SIC codes.
• Officers: every director and secretary, with appointment dates and other directorships as a join path.
• Persons with significant control (PSC): beneficial owners holding more than 25% — the layer most registries hide.

How do you query the Companies House API?

A Companies House query is a plain HTTP GET with basic auth — the API key goes in the username field and the password stays blank. We tested the endpoints on 2026-07-24; the pattern:

• GET /company/{company_number} returns the company profile.
• GET /company/{company_number}/officers returns directors and secretaries.
• GET /company/{company_number}/persons-with-significant-control returns beneficial owners above the 25% threshold.
• Pass an OE-prefixed number to the same PSC endpoint to read the Register of Overseas Entities — foreign companies holding UK property.

curl -u "YOUR_API_KEY:" \
  "https://api.company-information.service.gov.uk/company/00000006/persons-with-significant-control"

According to Companies House documentation, the rate limit is 600 requests per 5-minute window per key — enough for roughly 172,000 lookups a day. Endpoint, auth, and limits in one table: the Companies House access card.

What makes the PSC register different from other registries?

The PSC register is a beneficial-ownership layer: since 2016, UK law requires companies to declare every person or entity controlling more than 25% of shares or voting rights. Most company registries stop at the legal shell; the PSC register names who actually stands behind it, with nationality, country of residence, and nature of control. In our data, this is the highest-leverage UK dataset for due diligence: chains of shell companies collapse once you follow PSC links two or three hops. Companies House also publishes the full PSC file as a free bulk snapshot — we track it as a separate source for batch workloads, so you crawl the API only for fresh deltas rather than the whole register.

Can you search UK companies by name for free?

Yes — the same API has a search endpoint, and local open-data portals add regional slices. In our catalog, the Camden borough portal alone republishes 801,903 Companies House records filtered to London postcodes, queryable by name, address, and date range without any key. The practical free stack for UK company work:

• Companies House API: profile, officers, PSC — the authoritative record.
• PSC bulk snapshot: full beneficial-ownership file for batch joins.
• HM Land Registry OCOD/CCOD files: which companies own UK property, joinable by company number.

That combination answers UK company-lookup, ownership, and property questions at zero data-license cost — the paid tier only becomes necessary for monitoring at scale. For chains that leave the UK, the GLEIF LEI register supplies the cross-border join key between national registries.

Test page. Endpoints and limits as probed on 2026-07-24 via the Aidenix Atlas catalog. Not yet editorially reviewed.