# Registrum

> UK company data API on top of Companies House: financials parsed from iXBRL filings (turnover, profit, net assets, employees), directors and director networks, PSC beneficial-ownership chains, and identity-verification status - as clean JSON, with no Companies House API key or 600-requests-per-5-minutes limit to manage. Also available keyless over MCP.

## Try it with no key

- [Hosted MCP endpoint](https://registrum.co.uk/api/mcp): Point any MCP client (Claude, Cursor and others) at https://registrum.co.uk/api/mcp - no signup, no key, no install. Claude Code: `claude mcp add --transport http registrum https://registrum.co.uk/api/mcp`. Tools: search_company, get_company, get_financials, get_directors, get_network, get_psc, get_psc_chain, get_compliance, get_bundle, plus search and fetch for ChatGPT connectors and deep research.
- [MCP setup guide](https://registrum.co.uk/mcp): Setup for Claude Desktop, Claude Code, Cursor and other MCP clients, plus the local npm package `@registrum/mcp`.

## Docs

- [Quickstart](https://registrum.co.uk/quickstart): Integrate the Registrum Companies House API in 10 minutes. Step-by-step guide: register, make your first call, explore financials, deploy to production.
- [API reference](https://api.registrum.co.uk/docs): Full OpenAPI reference for every Registrum endpoint.
- [Companies House API rate limit](https://registrum.co.uk/companies-house-api-rate-limit): The official 600 requests per 5 minutes rule, the X-Ratelimit response headers, a retry and backoff function, what triggers a ban, and how to batch.
- [Companies House API key not working](https://registrum.co.uk/guides/companies-house-api-key-not-working): Fixing 401, 400 and 403 errors on the official API: Basic auth with an empty password, key types, sandbox vs live, browser Origin blocks.
- [How to get a Companies House API key](https://registrum.co.uk/guides/how-to-get-a-companies-house-api-key): Step by step on the developer hub, with a first call in curl and Python.
- [Python client](https://pypi.org/project/companies-house/): `pip install companies-house`. Open-source client for the official Companies House API with rate-limit handling built in, plus a Registrum class for financials and PSC chains.
- [Registrum vs the Companies House API](https://registrum.co.uk/vs-companies-house): Field-by-field comparison of what each returns.

## Product

- [iXBRL Parser API](https://registrum.co.uk/ixbrl-parser-api): Parse UK company iXBRL filings from Companies House into clean JSON. Structured turnover, profit, net assets.
- [Director Network API](https://registrum.co.uk/director-network-api): Discover UK company networks via shared directors. One API call traverses the full director graph to 2 degrees.
- [Beneficial Ownership API](https://registrum.co.uk/beneficial-ownership-api): Resolve ultimate beneficial owners for any UK company via the PSC register. Decoded control types, active/ceased split, and recursive chain traversal.
- [Bulk Enrichment API](https://registrum.co.uk/bulk-enrichment): Enrich 500 UK companies with a single API call. Companies House rate limit handled automatically.
- [Search](https://registrum.co.uk/search): Search any UK company by name and get live data from Companies House.
- [Company report](https://registrum.co.uk/report): One-off UK company compliance report - director network, PSC chain, risk flags, delivered to your inbox within 60 seconds.

## ECCTA identity verification (for accountants and compliance teams)

- [ECCTA verification](https://registrum.co.uk/eccta-verification): Check ECCTA identity verification status for UK company directors and PSCs. Mandated from November 2025, with enforcement beginning November 2026.
- [Guides](https://registrum.co.uk/guides): Index of all Registrum guides on ECCTA identity verification and Companies House compliance.
- [Confirmation statement identity verification](https://registrum.co.uk/guides/confirmation-statement-identity-verification): What confirmation statement identity verification requires: who must verify before you file a CS01, what blocks the filing, and how to check status first.
- [How to check a director's identity verification status at Companies House](https://registrum.co.uk/guides/companies-house-identity-verification-check): Three ways to check whether a UK company's directors and PSCs have completed ECCTA identity verification: the register, a free online checker, and the API.
- [The ECCTA deadline for accountants](https://registrum.co.uk/guides/eccta-deadline-accountants): ECCTA identity verification enforcement begins 18 November 2026. A practical checklist for accountancy firms and advisors responsible for many client companies.
- [Confirmation statement rejected because of an unverified director?](https://registrum.co.uk/guides/unverified-director-confirmation-statement): Since 18 November 2025, Companies House rejects a confirmation statement if any director has not completed identity verification. Why it happens and how to fix it.

## Pricing

- Free tier available - no credit card required. See the homepage for the full plan comparison: https://registrum.co.uk/#pricing
- Canonical, machine-readable plan data (quotas, limits, prices): https://api.registrum.co.uk/v1/plans

## Contact

- support@registrum.co.uk