Companies House Watchlist — change alerts, not another snapshot

Give it a list of UK company numbers and your own free Companies House API key. Run it again later (daily, weekly — however you schedule it) against the same list, and instead of another static export it tells you only what changed since last time:

• a director or secretary was appointed or resigned
• a person with significant control (PSC) was added or ceased
• a charge (mortgage/security interest) was newly registered — a real signal that the company just took on new secured lending/finance — or an existing charge was satisfied (paid off)
• a new filing appeared in the company's filing history
• the company's own status changed (e.g. active → dissolved, active → administration), or an insolvency-history flag started

The first run for any company is a baseline: it stores the current state and reports zero changes (nothing to compare against yet). Every run after that reports real deltas.

Why this and not the other Companies House Actors

The Apify Store already has several Companies House Actors — checked live, 27 September 2026, via the Store's own public API (api.apify.com/v2/store?search=companies house):

Every one of them is a snapshot tool: point it at a company and it hands back the current state. None of them keep any memory of a previous run, so none of them can answer the question a compliance analyst, credit team or sales-intelligence user with an existing watchlist actually asks: "has anything happened since I last checked?" This Actor is built specifically to answer that question — it stores each company's snapshot in its own Apify key-value store between runs and diffs the new snapshot against it, so scheduling it (e.g. once a day) turns it into an actual monitoring feed instead of a repeated manual lookup.

Data source

Everything comes from the UK government's own official, free Companies House Public Data API (api.company-information.service.gov.uk, documented at developer-specs.company-information.service.gov.uk). No scraping of the find-and-update.company-information.service.gov.uk website, no ToS issue: this is Companies House's own REST API, built for exactly this kind of integration. A free API key takes about two minutes to register at developer.company-information.service.gov.uk — no card, no approval wait, no paid tier required for the endpoints this Actor uses (company profile, officers, PSCs, charges, filing history).

Verified live (27 September 2026, unauthenticated): a request to GET /company/00000006 without a key returns HTTP 401 {"error":"Empty Authorization header","type":"ch:service"} — confirming the endpoint is live and that a key is the only credential needed.

Input

• Companies House API key (your own, free, marked secret) — required
• Company numbers — one per line, or paste a block of text (commas/ semicolons/newlines all work). Plain numeric numbers are zero-padded to 8 digits automatically (6 → 00000006); Scottish (SC), Northern Irish/other (NI, R0) and LLP (OC, SO) prefixes are kept as given.
• Toggle which categories to watch: officers, PSCs, charges, filings (all on by default)
• Concurrency (1–10; Companies House's public API allows 600 requests per 5 minutes per key — keep this low if you watch all four categories, which is up to 5 requests per company per run)

Output (one row per company per run)

{
  "company_number": "00000006",
  "company_name": "EXAMPLE COMPANY LIMITED",
  "company_status": "active",
  "is_baseline_run": false,
  "changes_found": 2,
  "changes": [
    {
      "event": "charge_registered",
      "detail": "New charge #3 (A registered charge) registered on 2026-09-20 in favour of Big Bank plc",
      "data": { "...": "full charge record" }
    },
    {
      "event": "officer_resigned",
      "detail": "Jane Doe (director) resigned on 2026-09-22",
      "data": { "...": "full officer record" }
    }
  ],
  "current_officer_count": 4,
  "current_psc_count": 1,
  "current_open_charge_count": 2,
  "status": "ok"
}

A company with no changes since last run still gets a row (

changes_found: 0

Pay-per-event

The custom event company-checked is charged once per company that was actually reachable on the register (status: "ok"), whether or not any change was found — a "nothing changed" result is still a real check you paid to have run. not_found and unauthorized rows are not charged.

Honest limits (kept out rather than faked)

• This Actor watches officers, PSCs, charges, filing history and company status — it does not parse company accounts/financials (iXBRL); that is a materially different parsing job other Actors in this niche specialise in, and adding a shallow version here would risk wrong numbers rather than a real feature.
• The "baseline" run intentionally reports zero changes even though, e.g., every existing officer looks "new" internally — reporting a company's entire existing officer list as if it just happened would be misleading on day one; real alerts start from run two.
• Companies House's officer/PSC records do not expose a single stable numeric ID in the public API the way an internal database would; this Actor keys officers/PSCs by their links.self/appointment link (stable per person per role) and falls back to name — matched. If Companies House itself renames or re-issues a link, a resignation+reappointment could show as officer_removed_from_register + officer_appointed rather than a single event; this is documented rather than silently hidden.

Related Actors in this account

• corporate-kyc-intelligence — GLEIF LEI ownership tree & compliance flags for any company worldwide (single-lookup, not UK-specific, not a watchlist)
• uk-planning-applications — UK local council planning application search/monitoring via the PlanIt API