ChangeDetection: Free Open Source Website Monitoring and Alert Tool
Monitoring changes on websites is a critical requirement for many use cases: tracking competitor updates, following price changes, monitoring documentation, or simply ensuring that important pages do not change unexpectedly. While many commercial tools exist, they often come with limitations, opaque logic, or recurring costs.
ChangeDetection is a free, open source website monitoring and alert tool designed to give users full control and transparency. It allows you to track changes on any webpage, configure how those changes are detected, and receive notifications when something meaningful happens — all without vendor lock-in.
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Dashboard
The ChangeDetection dashboard is the central control panel for all monitored websites. It provides a clear, consolidated view of:
- All tracked URLs
- Their current status
- The time of the last check
- Whether changes have been detected
The interface is designed to be minimal and efficient, allowing users to quickly understand what has changed and what requires attention. From the dashboard, you can access individual monitors, review change history, or adjust settings without unnecessary navigation.
Track Changes on a Website
At its core, ChangeDetection allows you to monitor any website by simply providing a URL. Once added, the tool periodically fetches the page and analyzes its content based on your configuration.
ChangeDetection supports multiple change detection methods, enabling you to track:
- Full page content
- Specific HTML elements
- Textual differences only
- Visual or rendered output (depending on setup)
This flexibility makes it suitable for both simple monitoring needs and advanced, fine-grained use cases.
Changes & History
Every detected change is recorded and stored, allowing you to review the full history of a monitored page. The history view highlights what exactly changed between versions, making it easy to identify meaningful updates versus noise.
This historical tracking is especially useful for:
- Auditing changes over time
- Comparing previous and current versions
- Understanding long-term trends on monitored pages
Nothing is overwritten — you always retain visibility into past states.
Frequency, Filters, & Notifications
ChangeDetection offers precise control over when and how monitoring occurs.
You can configure:
- Check frequency (from frequent polling to more relaxed intervals)
- Filters to ignore irrelevant or dynamic content
- Notification triggers based on specific conditions
Notifications can be sent through multiple channels depending on your setup, ensuring you are alerted immediately when something important changes — without being overwhelmed by false positives.
Groups
For users monitoring many websites, ChangeDetection supports grouping. Groups allow you to organize monitors by project, client, topic, or any logical structure that fits your workflow.
This improves clarity, simplifies navigation, and makes large-scale monitoring manageable. Group-level actions and visual separation help keep complex setups under control.
API & Chrome Extension
ChangeDetection provides an API that enables automation and integration with external systems. This makes it possible to:
- Programmatically manage monitors
- Retrieve change data
- Integrate alerts into internal tools or workflows
In addition, the Chrome extension allows users to quickly add pages to ChangeDetection directly from the browser, streamlining the setup process and reducing friction for day-to-day use.
Conclusion
ChangeDetection is a powerful yet accessible solution for website change monitoring. By being free and open source, it offers transparency, flexibility, and long-term control that proprietary tools often lack.
Whether you are tracking a single webpage or managing a large monitoring setup, ChangeDetection provides the essential features — dashboards, history, filtering, notifications, and integrations — needed to monitor the web reliably and efficiently.