Website Change Detector

What does Website Change Detector do?

Website Change Detector is an Apify actor that monitors web pages for content changes by computing and comparing content hashes across runs. It can track changes to entire pages or specific sections using CSS selectors, making it perfect for monitoring sites like Hacker News or any page where timely change detection matters. Each run outputs whether the content has changed along with hash values and content length for comparison.

Why use Website Change Detector?

• Automated monitoring -- Detect changes on competitor pages, pricing tables, documentation, or news feeds without manual checking.
• CSS selector targeting -- Monitor only the part of a page that matters, such as a product price or a specific section of content.
• Hash-based comparison -- Uses content hashing for fast, reliable change detection that works regardless of page size.
• API integration -- Trigger downstream workflows when changes are detected using the Apify API.
• Proxy support -- Access geo-restricted or rate-limited pages through Apify Proxy.

How to use Website Change Detector

1. Go to the Apify Store and search for Website Change Detector.
2. Click Try for free to open the actor in Apify Console.
3. Enter the URLs you want to monitor in the URLs field.
4. Optionally set a CSS Selector to target a specific element on the page (defaults to body).
5. Click Start to run the check. Set up a schedule for recurring monitoring.

Input configuration

Field	Type	Description	Default
urls	Array of strings	URLs to monitor for changes	["https://news.ycombinator.com"]
selector	String	CSS selector to monitor specific content	"body"

Output data

Each record represents one monitored URL and includes the change status, current and previous content hashes, and the content length in characters.

{
  "url": "https://news.ycombinator.com",
  "hasChanged": true,
  "currentContentHash": "a3f2b8c1e9d4507fab12de3456789abc",
  "previousContentHash": "7e9c1d5a2b8f4360cde789ab01234567",
  "currentContentLength": 48523
}

Cost of usage

Website Change Detector uses pay-per-event (PPE) pricing at the Mid tier:

Tier	Cost per 1,000 events	Free events per month
Mid	$0.75	~6,600

Each URL checked costs approximately 1 event. Monitoring 20 URLs daily (600 checks per month) would cost roughly $0.45 total, well within the free tier. Even aggressive monitoring schedules with hundreds of URLs remain highly affordable.

Tips and advanced usage

• Set up scheduled runs -- Use scheduled runs to check pages hourly, daily, or weekly and get notified when content changes.
• Use precise selectors -- Instead of monitoring the entire body, target a specific element like #price or .main-content to reduce false positives from ads or dynamic widgets.
• Trigger webhooks -- Configure an Apify webhook to send a Slack message or email whenever hasChanged is true.
• Track content length trends -- Monitor currentContentLength over time to detect significant additions or removals of content.
• Combine with screenshots -- Pair this actor with a screenshot tool to capture visual evidence of changes alongside hash-based detection.

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Built with Crawlee and Apify SDK. See more scrapers by consummate_mandala on Apify Store.