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Companies House API🇬🇧 UK register · enriched
Companies House API: UK company data in one REST call
The Companies House API is free and solid for registry lookups. What it does not return: contact details, employee counts, or financials as structured data. CompanyData delivers 8.8M+ UK records with all of that, in one REST API.
Free trial credits · No card required · Same API covers 200+ countries
8.8M+
UK business records
50+
data points per record
SIC 2007
official UK codes on every record
<200 ms
median response
GET /api/company/search?nationalId=09446231
MONZO BANK LIMITED
London, United Kingdom
Company number09446231
UK SIC 200764191 · Banks
+ Enriched by CompanyData
Employees1,000 to 5,000
Revenue range£100M+
Email and websiteh•••@monzo.com · monzo.com
Source: Companies House + enrichment · sample200 OK · 143 ms
The basics
What is the Companies House API?
Companies House is the UK registrar, an executive agency of the Department for Business and Trade, with 5.4 million registered entities identified by an 8-character registration number. Its official REST API is free after developer registration and good at what it does.
Its boundaries are structural: the register holds no contact details and no employee counts, accounts arrive as iXBRL documents rather than JSON fields, and shareholder detail sits inside confirmation-statement documents. CompanyData enriches that foundation with the same registration numbers and UK SIC codes, plus revenue, employees, email, phone and website, filterable through one API that also covers 200+ other countries.
The official API, in short
- Free key, covering profile, officers, PSC data and filing history
- 600 requests per 5 minutes, plus streaming and monthly snapshots
- No contact details, no employee counts
- Accounts as iXBRL documents, not JSON fields
- One country, so separate integrations for the rest
Try it live
Search any UK business
Register fields plus the enrichment layer, in one response. Pick a business, no key needed for the sample.
- Official UK SIC 2007 codes on every record
- Revenue and employees as structured fields, not iXBRL
- Email, phone and website where available
Side by side
Companies House API vs CompanyData, per data point
The Companies House API covers the register well. CompanyData delivers 50+ enriched data points per UK business in a single call.
| Data point | Companies House | CompanyData API |
|---|---|---|
| Businesses in the file | 5,516,377 | 8,818,829 |
| Registered name and trading names | 5,516,377 | 8,818,829 |
| Company number | 2,451,164 | 5,789,251 |
| Registered address and postcode | 3,185,080 | 8,815,924 |
| UK SIC 2007 code and type | 3,185,208 | 8,818,829 |
| Incorporation date and status | 3,185,208 | 8,818,829 |
| Directors and officers | ✗ | 6,294,256 |
| Website | ✗ | 2,658,687 |
| Telephone number | ✗ | 2,659,463 |
| Mobile number | ✗ | 885,347 |
| Business email address | ✗ | 1,265,877 |
| Revenue and employee bands | ✗ iXBRL documents | ✓ Structured fields |
| Group structure | ✗ | ✓ Included |
| International records | ✗ | 365M+ worldwide |
Our column counts every registered UK entity we hold, active or not, measured live in our own file, September 2026, and refreshed monthly. Companies House put 5,516,377 companies on the register at 30 June 2026, of which 548,411 were in dissolution or liquidation. We keep those: a dormant holding is still an entity worth resolving.
Access and filters
Companies House is built for per-entity lookups and bulk files. CompanyData adds segmentation on top: filter by SIC or industry, revenue, employees, region or city, and bulk-export with enrichment included.
Price
Companies House is free, and stays the right tool for registry-only lookups. CompanyData adds the enrichment layer from €0.02 per credit, with free trial credits and one API for 200+ countries.
See the difference
Look up any UK business, enriched
More data fields than Companies House returns: directors, revenue, employee counts and phone numbers, one lookup away. Defaults to the UK, switch country if you must.
Try one:
Just need a Companies House address file?
No integration, no code. The same enriched register as a ready-made Excel or CSV file: pick your SIC codes, regions and sizes, get a free sample first.
Best practice
Working with the official Companies House API
The official API is a good product with sharp edges. Here is how to get a key in three steps, and the six things that cost small teams the most time, whether you enrich with us or not.
1
Create a developer account
Register on the official Companies House developer hub. A standard account is free.
2
Register an application
Create an application for the live environment and generate a REST API key from its settings.
3
Call it with basic auth
Send the key as the HTTP basic auth username with an empty password, and stay under 600 requests per 5 minutes.
Honestly: the official API is perfect if you need free registry lookups or form autocomplete. If you need the complete picture, directors, contact details, structured financials and an uptime SLA, that is us.
Get your API key01
The key goes in basic auth, as the username
Register on the developer hub, create an application and use the key as the HTTP basic auth username with an empty password. Most 401s come from putting it in a bearer header instead.
02
Budget for 600 requests per 5 minutes
The limit is per key, and a 429 tells you to back off. Enriching a list of any size through the REST API takes hours; for one-off lists the free bulk snapshot is the better tool.
03
Company numbers are strings, not integers
Eight characters, leading zeros included: 445790 is 00445790. Scottish and Northern Irish numbers start with SC or NI. Trimming zeros in a spreadsheet is the classic silent bug.
04
Monitor with the streaming API, not polling
For dissolutions and officer changes, the streaming API pushes changes to you. Re-polling profiles burns your rate limit on records that did not change.
05
Accounts are documents, not fields
The filing history returns iXBRL files. If you need revenue or employees as numbers to filter on, you either build a parser or use an enriched source.
06
Officers and PSC data are separate calls
Profile, officers and PSC entries are three endpoints, so a full picture of one business costs several requests. Plan your rate budget accordingly.
Use cases
What teams build on UK register data
KYB and onboarding
Verify UK counterparties by registration number. Check status, officers and PSC data automatically.
Lead generation
Build prospect lists filtered by UK SIC code, region, revenue or business size.
CRM enrichment
Append registration numbers, SIC codes, financials and contacts to your UK accounts in bulk.
Risk and compliance
Monitor dissolutions, liquidations and officer changes across your UK supplier base.
UK form autocomplete
Type-ahead on registered names in signup and checkout forms, so the CRN and address arrive spelled the way the register spells them.
ERP and finance systems
Match suppliers and customers in your ERP to a company number once, then keep names, status and addresses in sync automatically.
Beyond the UK
The UK is one of 200+ countries on the same API
Same request shape, same response schema, from Companies House to the Handelsregister, KVK and Sirene. Build the UK integration once and take it worldwide.
Explore the Company Data API
More local registers
The same API, register by register
Customer stories
Sumsub, Veriff and BankID build on register data
Onboarding, KYB and supplier checks in production, on the same search and export calls that power the UK records above.
BankID · Digital identity
Live business KYC inside BankID
Norway's national trust mark verifies businesses against the register in real time, cutting verification time by 99%.
Read the story
Cellbunq · KYB
Global KYB compliance on one integration
Up-to-date business details from around the world, screened straight inside the onboarding flow.
Read the story
Zen.com · Fintech
Customer onboarding without the friction
Large-scale KYB verification through business lookup, built straight into the signup path.
Read the story
Sumsub · KYB platform
Verifying the address and the director, at scale
350M statutory addresses and registry director records inside Sumsub's global KYB flows, so shell offices and nominee directors get caught at onboarding.
Read the story
Veriff · Identity verification
UBO checks where the paperwork is hardest
Registry-sourced business and UBO data across Africa, Asia and Latin America, with 80% fewer manual reviews.
Read the storyCompanies House API Pricing
Transparent, credit-based pricing. Start with a free trial.
The enrichment layer
From €0.02 per credit
- Free trial credits on signup, key issued instantly
- Predictable credit pricing, plan-based rate limits that scale
- Bulk export with enrichment included, not just registry snapshots
Questions? Ask a human.
No ticket queue. Your question lands with our data team and you get an answer within 24 hours.
Amsterdam HQVijzelgracht 53D · +31 20 705 2360
BerlinFriedrichstraße 123 · +49 30 21480480
DubaiBuilding A1, Dubai Digital Park, Dubai Silicon Oasis
Mon to Fri 9:00 to 17:30 CET · info@companydata.com
What our customers say
Real feedback from the people using CompanyData every day.
★★★★★
The best data company we have worked with.
Helmut Huberti, M.D.
World Arthrosis Org., Heidelberg
★★★★★
Great feedback from our team on the data quality.
Stefania Guerra
Dyson, Milan
Frequently asked questions
Is the Companies House API free?
Yes. Register on the developer hub, create an application and you get a key with a 600-requests-per-5-minutes limit, plus free bulk snapshot files. The register itself simply does not hold contact details, employee counts or structured financials, which is where CompanyData comes in.
How do I get a Companies House API key?
Create an account on the Companies House developer hub, register an application and generate a key. Authentication is HTTP basic auth with the key as username. For enriched UK data, CompanyData issues an API key instantly on signup with free trial credits.
Does the Companies House API include financials?
Filed accounts are available as iXBRL documents through the filing history, not as structured JSON fields. CompanyData provides revenue and employee figures as structured fields on UK records, ready to filter and sort on.
Does CompanyData include UK SIC codes?
Yes. Every UK record carries the official UK SIC 2007 codes from the register, next to international SIC and NACE codes, and you can filter searches by SIC to build industry-specific lists.
What is the best Companies House API alternative?
For registry-only lookups, the official API is excellent. When you need contacts, employee counts, structured financials or industry filtering, CompanyData enriches 8.8M+ UK records in one REST API that also covers 200+ other countries.
How many UK businesses does CompanyData cover?
8.8M+ UK business records including active and historically registered entities, sole traders and branches, updated continuously from the register and other official sources.
Make 150 Free API Calls Before You Spend Anything
Tell us which UK businesses you need. You get a trial key with 150 lookups and 10 exports, plus a real sample response for your target market, within 24 hours.
or call +31 (0)20 705 2360