UK Data Layer API

Getting started

All endpoints live under https://api.ukdatalayer.com/v1. Requests are GET unless stated otherwise, and every response is JSON.

Authentication

Authenticate in whichever of these three ways suits your client:

# 1. Query string
curl "https://api.ukdatalayer.com/v1/company?key=YOUR_KEY&company_number=00000042"

# 2. Bearer token
curl "https://api.ukdatalayer.com/v1/company?company_number=00000042" \
  -H "Authorization: Bearer YOUR_KEY"

# 3. Custom header
curl "https://api.ukdatalayer.com/v1/company?company_number=00000042" \
  -H "X-API-Key: YOUR_KEY"

Credits

Each plan includes a monthly credit allowance and every request costs exactly 1 credit, whichever endpoint you call — no credit calculus. The cost is returned as credits_used on every response. Failed requests — bad parameters, unknown company numbers, server errors — never consume credits.

Check your balance any time with /account/credits, which is free to call.

Rate limits & CORS

Requests are limited to 10 per second on Build and 50 per second on Scale. Exceeding the limit returns 429 with a Retry-After header. CORS is enabled, so the API can be called directly from a browser — though you should proxy through your own backend rather than exposing a key client-side.

Response conventions

• Missing means missing. A field that was not disclosed returns null, never 0. Most small UK companies are not required to publish a profit and loss account, so a null turnover is normal and expected.
• Dates are ISO 8601. Always YYYY-MM-DD. Officer dates of birth are month precision only (YYYY-MM), as published.
• Money is a plain number in GBP. No currency symbols, no strings, no minor units.
• Company numbers are forgiving. 42, 00000042 and UK-00000042 all resolve to the same company.

Endpoints

10 endpoints across 6 groups. Every one takes your API key and returns the same response envelope.

Data coverage

The register covers 5.48m companies across all four UK nations. What varies is not the jurisdiction but the disclosure — small companies file less, and the PSC regime only began in 2016.

Known limits

• Turnover and profit are only available where a company chose or was required to file them. Roughly three quarters of companies have no disclosed turnover.
• Shareholder registers come from annual confirmation statements, so a holding can be up to twelve months out of date. Officer and PSC changes are filed within days.
• Business intelligence requires a verified website. Companies with no web presence return no_data rather than a guess.
• Officer dates of birth are published to month precision, so two people sharing a name and birth month cannot always be separated.

Error reference

Every response carries a status field. Errors add a message explaining what went wrong.

{
  "status": "error",
  "code": 404,
  "credits_used": 0,
  "message": "No company found with number 99999999"
}