Spotlight
Companies House API Integration for Lead Generation
Blumac Digital built a Companies House integration into blu::campaign, our email marketing platform. It turns the public register into a targeted prospect list. Search live company data by SIC code, location, incorporation date, company type and status, pull a named contact from the officers register, and import the results straight into a mailing list.
The brief
The challenge
Every UK limited company is on the public register, and Companies House gives that data away through a free API. The problem is shape, not access. The API answers questions about one company at a time, returns names in a format nobody would put in an email, and has no concept of a marketing list. Getting from "companies like this" to "a list I can write to" is the work, and most businesses do it by hand in a spreadsheet.
Why bespoke?
Off-the-shelf lead lists are sold to everyone, go stale, and rarely say where the data came from. Building against the register directly means the data is current on the day you pull it, you can see exactly which filters produced it, and the list belongs to you. The integration lives inside blu::campaign, so the results land in a mailing list ready to send rather than in another export waiting to be tidied up.
What it delivered
Precise Targeting
Lists are built from the register's own filters, so a search can be as narrow as active companies in one SIC code, in one area, incorporated in a given date range.
A Real Named Contact
The officers register supplies a current director's name for each company, so mail can open with a person rather than "Dear Sir or Madam".
Cleaner Data From The Start
Companies registered at shared formation agent and virtual office addresses are flagged automatically, so a list is not quietly full of accommodation addresses.
No Manual List Building
A search that would take days in a spreadsheet runs as a queued import, with progress reported as it goes and the results already in a mailing list at the end.
Our solution
What we built
A Companies House API Integration Built Into blu::campaign
Advanced Search Across The Live Register
The integration runs the Companies House advanced search endpoint, filtering on SIC code, location, company status, company type, incorporation date range and name. The results are the register as it stands today, not a bought snapshot.
SIC Codes Held Locally
All 731 SIC codes are synced into the platform and kept up to date, so choosing an industry is a searchable list rather than a code you have to look up first.
Named Contacts From The Officers Register
For each company the integration reads the officers register and takes the first current human director, skipping companies whose only officer is another company. Names come back from Companies House in capitals and surname first, so they are reformatted into something you can actually put at the top of an email.
Formation Agent And Virtual Office Detection
Addresses used by many different companies are the fingerprint of a formation agent or a mail forwarding service. Those addresses are detected and flagged, and a set of well known ones ships with the platform, so the quality problem is visible before you send rather than after.
Queued Bulk Import With Live Progress
Large result sets are imported page by page as background jobs, so a big search never hits a timeout, and progress is reported to the screen while it runs.
Built To Respect The API's Limits
Companies House rate limits its API and answers an empty search with an error rather than an empty result. The client handles both properly, so an import slows down and continues instead of failing halfway through.
Frequently asked questions
Is Companies House data free to use?
Yes. The register is public and Companies House publishes it through a free API, which needs a free API key rather than a subscription.
Reuse of the data is covered by Companies House's own terms, and most ordinary business use falls inside them. How you then contact those companies is a separate matter, governed by UK rules on marketing and data protection, and the rules differ depending on whether you are writing to a limited company or to a named individual.
We will build the integration and be straight with you about what the data can and cannot tell you. We are not lawyers, so take your own advice on your particular use before you start sending.
How current is the company data?
It is read from the register at the moment the search runs, not from a stored copy, so it reflects what Companies House holds that day.
That is the main difference from a bought list. A purchased list is a snapshot of whoever compiled it, on the day they compiled it, and it starts ageing immediately. Companies dissolve, change address and change directors constantly.
Can I filter by industry, location and how long a company has been trading?
Yes, and you can combine them. The available filters are SIC code for industry, location, incorporation date range, company status such as active or dissolved, company type, and words the company name does or does not contain.
All 731 SIC codes are held in the platform, so choosing an industry is a searchable list rather than a code you have to look up somewhere else first.
Can I get a named contact rather than writing to “The Directors”?
Yes. For each company the officers register is read and the first current human director is taken, so mail can open with a person's name. Companies whose only listed officer is another company are skipped, because there is no person to address.
One thing worth being clear about: this gives you a director's name, not an email address. Companies House does not publish personal email addresses, and no integration can invent them. The registered address is available, which is why this works particularly well for postal campaigns.
What is a formation agent address, and why does it matter?
A great many companies are registered at a company formation agent or a mail forwarding service rather than at anywhere they actually trade from. A single such address can have hundreds or thousands of unconnected companies registered to it.
For a postal campaign that is wasted print and postage, and for any campaign it is a poor signal of a real business. Addresses shared by an unusual number of companies are detected and flagged automatically, and a set of well known ones ships with the platform, so you can see the problem before you send rather than after.
Ready to Build a Prospect List From Live Company Data?
Tell us who you are trying to reach, and we'll tell you honestly whether the register can find them.
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