# RunOnProof UK Companies House Entity Resolver

> RunOnProof UK Companies House Entity Resolver is a paid API for AI agents from cdo-production.up.railway.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Resolves a UK company's identity using Companies House data given a company number or legal name, returning candidate matches or a REVIEW flag on ambiguity.

## Facts

- Endpoint: POST https://cdo-production.up.railway.app/v1/gb/entities/resolve
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/runonproof-uk-companies-house-entity-resolver-eb31bb28
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_EDokd-XkcmIEc5VzgtdFv

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability runonproof-uk-companies-house-entity-resolver-eb31bb28 -d '<json body>'
```

Example prompt: Can you resolve the UK Companies House identity for 'Acme Widgets Ltd' with postcode SW1A 1AA before we onboard them as a supplier — use company name and postcode to find the right registered entity?

## When to prefer this

Use this endpoint when you need to resolve the legal identity of a UK-registered company prior to onboarding, contracting, or payment — especially when you have a company number or a legal name with a postcode. Prefer this over general web search when you need authoritative Companies House source-scoped identity data with structured candidate output and ambiguity signalling.

## Known failure modes

- Ambiguous name returns REVIEW status rather than a single resolved entity — caller must refine search or use company number
- Invalid company number format rejected by schema validation
- No matching entity found for the given name or number
- Service unavailable or upstream Companies House API timeout
- Idempotency key mismatch if header and body values differ

## How this service works

Resolve a UK Companies House entity before onboarding or contracting. Use a company number, or a legal name with optional postcode, to obtain source-scoped identity candidates. Ambiguity returns REVIEW; it does not imply good standing.

## Output

Returns one or more identity candidate records sourced from Companies House, each containing registered company details scoped to the Companies House source. If the name/postcode combination is ambiguous, the response includes a REVIEW status rather than a definitive match. A unique company number query typically returns a single resolved record.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "postal_code": {
   "type": "string",
   "maxLength": 20
  },
  "company_name": {
   "type": "string",
   "maxLength": 300,
   "minLength": 2
  },
  "company_number": {
   "type": "string",
   "pattern": "^(?:(?:[A-Z]{2}|[0-9]{2})?[0-9]{6}|[0-9]{8})$",
   "description": "Companies House company number, including any two-letter prefix when applicable."
  },
  "idempotency_key": {
   "type": "string",
   "pattern": "^[A-Za-z0-9._:-]{8,120}$",
   "description": "Caller-generated key. Send the identical value in the Idempotency-Key header."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/runonproof-uk-companies-house-entity-resolver-eb31bb28/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from cdo-production.up.railway.app](https://www.zero.xyz/host/cdo-production.up.railway.app/llms.txt)