# UK Companies House PSC Monitor (`titan_coder/uk-companies-house-psc-monitor`) Actor

Beneficial ownership changes are buried in filings and nobody watches them for you. This one tracks the PSC register of your companies and reports only new persons with significant control since your last check. Official free API; quiet days cost nothing.

- **URL**: https://apify.com/titan\_coder/uk-companies-house-psc-monitor.md
- **Developed by:** [Radu Furtuna](https://apify.com/titan_coder) (community)
- **Categories:** Business, Lead generation
- **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

$20.00 / 1,000 new psc detecteds

This Actor is paid per event. You are not charged for the Apify platform usage, but only a fixed price for specific events.

Learn more: https://docs.apify.com/actors/running/actors-in-store.md#pay-per-event

## What's an Apify Actor?

Actors are web data automations that power AI and operations. They run on the Apify platform to scrape websites, process data, connect APIs, and automate workflows.
In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours,
and optionally produces a well-defined JSON output, datasets with results, or files in key-value store.
In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server.
Actors are written with capital "A".

## How to integrate an Actor?

If asked about integration, you help developers integrate Actors into their projects.
You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready.
The best way to integrate Actors is as follows.

- **AI agents and MCP clients** — the [Apify MCP server](https://docs.apify.com/integrations/mcp.md) at `https://mcp.apify.com` (remote, streamable HTTP, OAuth on first use).
- **Agentic workflows and local Actor development** — [Agent Skills](https://apify.com/.well-known/agent-skills/index.json) with the [Apify CLI](https://docs.apify.com/cli/docs.md): `npm install -g apify-cli`, then `apify login`.
- **JavaScript/TypeScript projects** — the official [JS/TS client](https://docs.apify.com/api/client/js/docs.md): `npm install apify-client`.
- **Python projects** — the official [Python client](https://docs.apify.com/api/client/python/docs.md): `pip install apify-client`.
- **Any other language** — the [REST API](https://docs.apify.com/api/v2.md).

For usage examples, see the [API](#api) section below.

For more details, see Apify documentation as [Markdown index](https://docs.apify.com/llms.txt) and [Markdown full-text](https://docs.apify.com/llms-full.txt).

# README

## UK Companies House PSC Monitor

Durable monitor for new Persons with Significant Control (PSC — beneficial owners) registered against a
watchlist of UK companies, via the official, free Companies House "persons with significant control" API.

### Why

AML/KYC compliance teams, credit-risk analysts, and competitive-intelligence teams need to know the moment
a tracked company's beneficial ownership changes — a new PSC can signal a change of control, an acquisition,
or a compliance-relevant ownership shift. Existing scrapers on Apify only do a one-off pull; none durably
track what's already been seen and pay only for genuinely new PSC records.

### How it works

1. You provide **your own free Companies House API key** (register instantly at
   [developer.company-information.service.gov.uk](https://developer.company-information.service.gov.uk/) —
   no cost, no approval wait). We never store it beyond the run.
2. Each `watch` is one company you track by its `companyNumber`.
3. Every run fetches that company's current PSC list and diffs it against a durable checkpoint of PSC IDs
   already seen for that watch.
4. Genuinely new PSC records are pushed to the dataset and billed once each (`new-psc-detected`); checking
   a watch with nothing new costs nothing beyond the fixed platform run cost.

### Input

```json
{
  "monitorId": "my-watchlist",
  "chApiKey": "your-companies-house-api-key",
  "watches": [
    { "watchId": "competitor-a", "companyNumber": "12345678" }
  ],
  "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-psc-detected` — charged only for a PSC record 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 PSC record, 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

- PSC records ceasing to have control are not specially flagged as "removed" in this version — a re-added
  PSC after ceasing would only be flagged as new if it received a new PSC ID.
- `seenIds` per watch is capped (small — 200 — since a company's PSC list is normally short).
- We don't invent data: if the API response shape changes, or a watch's `companyNumber` is wrong / the API
  key is invalid, the run reports it honestly instead of silently returning zero results.

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

# Actor input Schema

## `monitorId` (type: `string`):

Name of this monitor's durable history (a-z, 0-9, dash; up to 40 chars).

## `chApiKey` (type: `string`):

Your own FREE Companies House API key (developer.company-information.service.gov.uk). Without it the Actor exits cleanly without fetching anything and without charging you — useful for a dry run, but you need a key for real monitoring. We never supply our own key.

## `watches` (type: `array`):

1-30 objects: {"watchId": "competitor-a", "companyNumber": "12345678"}. companyNumber is the 6-10 character Companies House registration number. New companies can be added later under the same monitorId.

## `notifyOn` (type: `string`):

new\_alerts — post the webhook only when new paid PSC records were delivered; always — post it every run; never — do not call webhookUrl at all.

## `webhookUrl` (type: `string`):

Optional. Receives a digest of delivered (paid) new PSC records as JSON. HTTPS only.

## Actor input object example

```json
{
  "monitorId": "my-watchlist",
  "watches": [
    {
      "watchId": "competitor-a",
      "companyNumber": "00000006"
    }
  ],
  "notifyOn": "new_alerts"
}
```

# Actor output Schema

## `results` (type: `string`):

Every row this run produced. Key fields: watchId, companyNumber, name, kind, notifiedOn, naturesOfControl.

## `coverage` (type: `string`):

What this run actually covered and what it charged for: per-target status and reason, rows delivered and rows billed. Enough to reconcile every charge against every row.

## `digest` (type: `string`):

A short human-readable summary of what this run found, written every run.

# API

You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup.

## JavaScript example

```javascript
import { ApifyClient } from 'apify-client';

// Initialize the ApifyClient with your Apify API token
// Replace the '<YOUR_API_TOKEN>' with your token
const client = new ApifyClient({
    token: '<YOUR_API_TOKEN>',
});

// Prepare Actor input
const input = {
    "monitorId": "my-watchlist",
    "watches": [
        {
            "watchId": "competitor-a",
            "companyNumber": "00000006"
        }
    ]
};

// Run the Actor and wait for it to finish
const run = await client.actor("titan_coder/uk-companies-house-psc-monitor").call(input);

// Fetch and print Actor results from the run's dataset (if any)
console.log('Results from dataset');
console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`);
const { items } = await client.dataset(run.defaultDatasetId).listItems();
items.forEach((item) => {
    console.dir(item);
});

// 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs

```

## Python example

```python
from apify_client import ApifyClient

# Initialize the ApifyClient with your Apify API token
# Replace '<YOUR_API_TOKEN>' with your token.
client = ApifyClient("<YOUR_API_TOKEN>")

# Prepare the Actor input
run_input = {
    "monitorId": "my-watchlist",
    "watches": [{
            "watchId": "competitor-a",
            "companyNumber": "00000006",
        }],
}

# Run the Actor and wait for it to finish
run = client.actor("titan_coder/uk-companies-house-psc-monitor").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print(f"💾 Check your data here: https://console.apify.com/storage/datasets/{run.default_dataset_id}")
for item in client.dataset(run.default_dataset_id).iterate_items():
    print(item)

# 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start

```

## CLI example

```bash
echo '{
  "monitorId": "my-watchlist",
  "watches": [
    {
      "watchId": "competitor-a",
      "companyNumber": "00000006"
    }
  ]
}' |
apify call titan_coder/uk-companies-house-psc-monitor --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,titan_coder/uk-companies-house-psc-monitor"
        }
    }
}
```

The hosted server signs you in with OAuth on first connect, so no API token belongs in this config. Clients without OAuth support can send an `Authorization: Bearer <APIFY_API_TOKEN>` header instead, using a token from API & Integrations in Apify Console (https://console.apify.com/settings/integrations).

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/xLa48VhqyGa5xx5Ak/builds/08Mg5rxEhyFe4cEKD/openapi.json