Type a UK company number and get the company from the Companies House register: name, type, status and registered-office town, live. The format is checked first, including the Scottish, Northern Irish and LLP prefixes.
A UK company number is eight characters and it carries no check digit. Companies incorporated in England and Wales get eight digits, padded with leading zeros — Tesco is 00445790, and the zeros are part of the number. A Scottish company starts with SC, a Northern Irish one with NI, and six digits follow.
Other prefixes name other kinds of entity: OC, SO and NC for limited liability partnerships, FC for an overseas company with a UK establishment, IP and RS for societies, CE for a charitable incorporated organisation. The validator accepts the real prefixes and rejects the rest, which is the only check the number allows.
The lookup sends the number to the Prometiam API, which holds the Companies House register, and returns the company name, type, current status and registered-office town. The number is matched exactly, leading zeros included; a name search runs when the input is not a number.
Directors, filings, corporate events, insolvency notices and the full record are one call away with a free key — 1,000 calls a month, no card. For the UK that includes officers, persons with significant control, the strike-off and overdue-accounts flags and the Gazette notices.
Do I need the leading zeros?
Yes for the lookup: 445790 and 00445790 are different strings and the register holds the eight-character form. The tool pads a bare number for you before searching.
Is the company number the same as the VAT or UTR number?
No. The company number is issued by Companies House at incorporation; the VAT number comes from HMRC on registration and the UTR is the tax reference. Only the company number is on the public register.
Can I do this in code?
Yes: GET /companies/search?company_number=00445790&country=GB with an API key returns the same record as JSON; the free tier covers 1,000 calls a month.