Monitor UK Companies House changes as delta events — without building your own polling pipeline

Companies House, the public register of UK companies, provides a free API for accessing company data. However, the API is a request/response system, not a real-time feed, requiring developers to build their own polling mechanism to track changes in company information. This involves storing snapshots of each company, comparing fields, and determining if changes warrant an alert. This process is time-consuming and requires ongoing maintenance.

To simplify this process, Steadfetch offers a hosted delta feed called companies-house-monitor. This service allows users to maintain a private watchlist and receive only the changes made to the companies on that list, in the form of validated JSON events. This approach eliminates the need for developers to build and maintain their own polling pipeline.

Each delta event contains a stable schema with information such as the company number, name, status, risk indicators, and a human-readable description of the risk. The events are sourced from public register data, making them compliant with the Open Government Licence v3.0. The service supports two types of watches: company watches, which track a single register record, and query watches, which are saved searches that can return multiple new companies.

To use the service, developers can install the Apify CLI, add their first watch, and schedule daily runs of the monitor. The first run delivers a baseline, and subsequent runs only deliver changes. These changes can be easily consumed by JavaScript or Python scripts. The Actor is priced based on the number of delta events, monitor checks, and run starts, with a free monthly credit for the Apify free plan.