UK Companies House New Company Monitor

Durable monitor for newly incorporated UK companies matching your filters — SIC code, name text, or registered-office location — via the official, free Companies House "advanced company search" API.

Why

Sales, lead-gen, and competitive-intelligence teams want to know the moment a new competitor or prospect registers with Companies House. Existing scrapers on Apify only do a one-off bulk pull; none durably track what's already been seen and pay only for genuinely new incorporations.

How it works

1. You provide your own free Companies House API key (register instantly at developer.company-information.service.gov.uk — no cost, no approval wait). We never store it beyond the run.
2. Each watch is a saved filter: sicCodes, companyNameIncludes, and/or location (at least one is required — otherwise the search would match every UK incorporation, thousands per day).
3. Every run re-queries a rolling 21-day incorporation window (registrations are sometimes processed a few days after filing) and diffs against a durable checkpoint of company numbers already seen for that watch.
4. Genuinely new companies are pushed to the dataset and billed once each (new-company-detected); checking a watch with nothing new costs nothing beyond the fixed platform run cost.

Input

{
  "monitorId": "my-watches",
  "chApiKey": "your-companies-house-api-key",
  "watches": [
    { "watchId": "fintech-london", "sicCodes": ["62012", "64999"], "location": "London" },
    { "watchId": "acme-competitors", "companyNameIncludes": "acme" }
  ],
  "notifyOn": "new_alerts",
  "webhookUrl": "https://example.com/webhook"
}

Add more watches later under the same monitorId — each watch keeps its own independent history.

Billing

Pay-per-event: new-company-detected — charged only for a company genuinely new since the previous check of that watch. The first check of a new watch establishes a baseline (no charge). Failed/blocked checks are never charged.

Delivery and charging guarantee: at-most-once

For a single detected company, the dataset write and the pay-per-event charge each happen at most once — never twice. This is not "exactly-once", and we do not claim it is: the right to perform an irreversible action (dataset write + charge) is granted by Apify's only atomic primitive, RequestQueue.addRequest(uniqueKey), in a separate named journal queue <prefix>-<monitorId>-claims. Apify's Key-Value Store has no CAS, no conditional write and no ETag, so a KV-based state machine cannot guarantee it and is kept for diagnostics only.

The trade-off is deliberate: if a run crashes after taking the claim, that event may be lost (it is closed as dataset_unknown / charge_unknown and is never re-delivered) — but you are never charged for it twice. "We never overcharge" is worth more than "we never miss a row".

Boundaries of the guarantee, stated honestly:

• it holds as long as the named claims queue exists. Anyone with account access can delete or recreate it from the Console/API, which starts the journal from scratch — an unavoidable boundary of any durable storage, not a defect of the protocol;
• it applies from the build that introduced the claim gate onward. Runs from older builds against the same monitorId are not covered, and old builds must not keep running on it;
• seenIds eviction (below) is a separate, independent source of possible re-billing.

Honest limits

• The incorporation window is 21 days deep every check (not "since last run") to absorb Companies House's own processing lag — a company that appears late is still caught by the rolling window, same as it would be missed if we only diffed against a hard cutoff.
• seenIds per watch is capped (FIFO by discovery order); if a watch has an extreme incorporation volume and evicted numbers reappear on the visible window edge, they can be re-billed. Use a narrower filter (more specific SIC code / location) to avoid this on high-volume watches.
• We don't invent data: if the API response shape changes or a watch's API key is invalid, the run reports it honestly instead of silently returning zero results.

Author: OmniCoder (https://t.me/OmniCoder)