Briefed Atlas
The Companies House API: what it gives you and where it stops.
The Companies House API is the starting point for most UK corporate data pipelines. It is free, reliable, and covers every registered entity. It is also raw, unresolved, and stops at the edge of the UK register. Here is what that means for teams building on top of it.
What the Companies House API covers.
The free public API gives you structured access to the Companies House register. These are the main data types available.
Company profiles
Registered name, number, address, incorporation date, SIC codes, and current filing status for all registered UK entities.
Officers
Current and resigned directors, secretaries and persons with significant control, with appointment and resignation dates.
PSC data
The persons with significant control register for each company: name, nature of control, and the band in which their interest falls.
Filing history
The full document history for a company, with links to the original filings as submitted.
Insolvency
Insolvency and dissolution records, including liquidation, administration and voluntary strike-off history.
What it does not give you.
The API returns data as it is in the register. What you do with that data is your problem. These are the gaps that teams building production pipelines typically discover after they have started.
Entity resolution across records
The same individual often appears under slightly different names, addresses or date-of-birth formats across different company filings. John William Smith at one address and J. W. Smith at another may be the same person. The Companies House API returns records as filed; matching them to a single identity is a separate problem that requires entity resolution on top of the raw data.
Chain resolution for corporate PSCs
If a company's PSC is itself a company, the API returns that corporate PSC record. Resolving who ultimately controls the structure requires calling the API again for the corporate PSC, and repeating until a natural person is reached. There is no endpoint that does this automatically.
Cross-registry data
Companies House covers UK-registered entities. A structure that includes Scottish limited partnerships, overseas companies or entities registered in other jurisdictions is not fully captured. Each jurisdiction requires a separate registry query, in a different format, with different fields and update frequencies.
Historical ownership at a point in time
The API shows the current state of a record and its amendment history separately. Reconstructing what a company's PSC register looked like on a specific date in the past requires reading through amendment events in sequence. There is no endpoint that returns the state of a record as it stood on an arbitrary past date.
Rate limits and reliability for production use
The free Companies House API tier has rate limits that constrain high-volume production use. Bulk data access is available through a separate streaming API, but requires additional setup and the data arrives in a format that still requires significant processing before it is queryable in a useful way.
Common questions.
Is the Companies House API free?
Yes. The Companies House API is publicly available and free to use. There are rate limits on the standard tier. Bulk data is also available at no charge through the Companies House streaming API, which provides full dataset access but requires more infrastructure to consume.
What is the Companies House API rate limit?
The standard API tier allows 600 requests per five-minute window, per API key. For production KYB or compliance pipelines processing significant volumes, this limit is a real constraint. The streaming API bypasses per-request limits but is a different integration model.
Can the Companies House API tell me who ultimately controls a company?
Not directly. The API returns the PSC record for a company, which shows the immediate person or entity with significant control. If that PSC is a company rather than an individual, you need to call the API again for that company. Chain resolution, tracing through corporate layers to a natural person, is not a native capability of the API.
Is there a Companies House API for bulk company data?
Yes. Companies House provides a bulk data product through their streaming API, which gives access to the full register rather than per-company lookups. The data is structured as a stream of events rather than a queryable database, so consuming it requires building a processing layer on top.
What is entity resolution and why does it matter for Companies House data?
Entity resolution is the process of recognising that two records refer to the same real-world person or company. Companies House filings are submitted by many different parties and contain variations in name spelling, address format, and date of birth. A director called "James A. Robertson" in one filing and "J. Robertson" in another may be the same person. Entity resolution matches these records to a single identity. Without it, a director with 40 appointments across different spellings looks like 40 different people.
The resolved layer above the raw register.
Briefed Atlas ingests Companies House data alongside other national registers, applies entity resolution across the corpus, resolves ownership chains to the natural person, and makes the result queryable over an API or in bulk. For engineering teams whose pipeline currently handles entity matching, chain resolution and cross-registry lookups manually on top of the Companies House API, Atlas moves that work into the data layer. You query resolved ownership; you do not build it.
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The ontology, the document corpus and the ownership graph, delivered into systems you already run, or worked directly by our team when the problem needs it.