company register

A company register is the official registry of legal entities kept by a corporate registrar - here the UK's Companies House. Its Public Data API serves "one record per legal entity, with nested officer, filing, charge, and PSC records" across several million active and dissolved entities.

Coverage is deep: live and real-time, with filings back to incorporation and records observed from 1862 onward; SIC 63110 alone matches ~48,674 companies (August 2026).

Two access routes exist: the free REST API (JSON, plus document and streaming APIs) and a monthly bulk CSV snapshot of every UK-registered company - ~470 MB zipped as one file or seven ZIP parts totalling ~460 MB, roughly 5-6 million rows, latest observed 2026-08-01.

The register is the source every commercial firmographics vendor resells, so differences come down to freshness, depth and licence handling.

• Real-time versus monthly is a real fork. The API reflects changes as they happen; the bulk snapshot is compiled to month-end (latest observed 2026-08-01).

• Nested records are the value. Officers, filings, charges and PSCs sit under each company; a flat extract loses ownership and compliance detail.

• History is long but not uniform. Filings reach back to incorporation, records to 1862, but digital completeness varies by era.

• Licensing needs care. Register data is Crown copyright within the GOV.UK framework, free but unsupported - check the reuse wording before commercial redistribution.

1. Confirm it is the register, not a subset. The bulk snapshot carries roughly 5-6 million live companies across seven parts; ask a vendor to state their count.
2. Test the nested records. Officers, filing history, charges and PSCs should each be present per company, as the API serves them.
3. Pin the snapshot date. Bulk data is monthly (latest observed 2026-08-01); undated extracts are unusable for compliance work.

Where to see it in context: data processing outsourced services data and research consulting services data.

These entries cover the access routes, licence and nested records a register exposes: - bulk download — Taking delivery of complete pre-packaged files rather than querying a live endpoint - the dominant access method here at 5 of the 8 pooled datasets.