Change detection is the process of automatically monitoring a website to identify when specific content has been added, removed, or modified. Instead of manually checking pages over and over, you set up a system that watches for differences and alerts you when something changes.
How change detection works
At its core, change detection compares two snapshots of a webpage taken at different times. The system extracts the relevant data from each snapshot, runs a comparison, and flags any differences it finds.
Here is the typical workflow:
- The system scrapes the target webpage and stores the data
- After a set interval (minutes, hours, or days), it scrapes the same page again
- It compares the new data against the stored version
- If differences exist, it triggers an alert or logs the change
You can monitor entire pages or focus on specific elements like prices, product availability, text blocks, or images. Most web scraping setups let you define exactly what you want to track, so you only get notified about changes that actually matter to you.
Common use cases
Price monitoring
E-commerce businesses track competitor prices in real time. When a rival drops their price on a popular product, your system catches it immediately. This lets you adjust your own pricing strategy before you lose sales.
Stock and availability tracking
Retailers and resellers monitor product pages to know the moment an out-of-stock item becomes available again. This is especially valuable for limited-edition products or high-demand inventory.
Content and news monitoring
Marketing teams and researchers track news sites, blogs, and regulatory pages for updates. When a competitor publishes a press release or a government agency updates compliance guidelines, you find out right away.
SEO and SERP tracking
SEO professionals monitor search engine results pages to see when rankings shift. Change detection helps you spot algorithm updates or competitor movements that affect your visibility.
Job and listing alerts
Recruiters and job seekers use change detection to monitor career pages for new openings. Real estate professionals track listing sites for new properties or price drops.
Key techniques
Text comparison: The system checks if the text content on a page has changed. This works well for articles, product descriptions, and policy pages.
Visual comparison: Some tools take screenshots and compare them pixel by pixel. This catches design changes, layout shifts, and image updates that text-based methods might miss.
Element-specific monitoring: Rather than watching an entire page, you target specific HTML elements. For example, you might only track the price tag on a product page and ignore everything else.
Hash-based detection: The system generates a unique fingerprint (hash) of the page content. If the hash changes, something on the page is different. This method is fast but does not tell you exactly what changed.
Why change detection matters for web scraping
Web scraping without change detection means you are collecting data blindly. You might scrape thousands of pages daily without knowing which ones actually updated. Change detection makes your scraping smarter by focusing your resources on what is new or different.
This approach also reduces unnecessary requests. Instead of pulling full data sets repeatedly, you only act when something changes. That saves bandwidth, lowers costs, and reduces the chance of triggering rate limits or blocks.
How Browse AI helps with change detection
Browse AI makes change detection simple without requiring any coding. You can set up monitors that automatically track specific data points on any website and receive alerts when changes occur. Whether you are watching prices, stock levels, or content updates, Browse AI handles the scheduling, comparison, and notifications for you.
The platform lets you define exactly which elements to monitor and how often to check them. When a change happens, you get notified through email, Slack, or other integrations. Visit Browse AI to start monitoring websites for changes in minutes.
