The UK's Economic Crime and Corporate Transparency Act 2023 ("ECCTA") changed Companies House from a passive filing repository into a verification authority. Identity verification for directors and PSCs is being rolled out in phases through 2026, suspended-name powers expanded, and there's a new "abbreviated information" mode for small filers. None of that broke the public REST API — but it changed what's in the data . If you're integrating Companies House in 2026, here's what the surface actually looks like, what's free, what's paywalled, and the quirks that bite if you don't know them. What's free and programmatic Companies House publishes one of the cleanest open registry APIs in the world. You sign up at developer.company-information.service.gov.uk , get an API key, and you're off. The API covers: Search — /search/companies returns up to 50 hits per call, paginated. There's a separate /search/officers and /search/disqualified-officers .…