On-Page Content Checker

What is the On-Page Content Checker?

The On-Page Content Checker is an automated web content detection tool, dedicated to monitoring specific content changes on web pages and tracking revision history. With CoreClaw, you can monitor web content with zero code, empowering use cases such as e-commerce price monitoring, news tracking, competitor analysis, inventory monitoring and more.

• ✅ Flexible Content Monitoring - Monitor specific content on any web page using CSS selectors
• ✅ Preset Selectors - Built-in drop-down menu of commonly used selectors, no need to manually write CSS
• ✅ Custom Selectors - Advanced users can enter custom CSS selectors to meet complex needs
• ✅ Automatic Screenshot Comparison - Automatically capture before-and-after comparison screenshots to intuitively display changes
• ✅ State Persistence - Pass the previous state through input parameters to achieve continuous monitoring
• ✅ Intelligent Retry Mechanism - Built-in retry function to automatically handle network issues
• ✅ Dynamic Content Support - Support waiting for dynamic content loading to ensure data accuracy
• ✅ CDP Remote Browser - Support CDP connection to remote fingerprint browsers to improve stability

What Data Can You Retrieve?

How to Use the On-Page Content Checker?

The CoreClaw On-Page Content Checker handles web page loading, content extraction, screenshot generation and change detection in the background for you. You can monitor web content in just a few minutes with the following steps:

1. Create a free CoreClaw account with your email
2. Open the web-based On-Page Content Checker control panel
3. Enter the list of web page URLs to be monitored
4. Select a content selector (preset or custom)
5. Configure screenshot selector and advanced parameters (timeout, wait time, etc.)
6. Click "Start" to get the initial content on the first run
7. On the next run, pass the results of the last run as "Previous Content" to automatically detect changes
8. Download the data containing change detection results in JSON format

➡️ Input

Key Parameter Description

Preset Selectors

Content Selector Presets

Screenshot Selector Presets

Usage Examples

Example 1: Monitor Hacker News Headlines

• URL: https://news.ycombinator.com/
• Content Selector: News Title (.titleline)
• Screenshot Selector: Use Content Selector (Default)
• Result: Monitor changes to news headlines, automatically detect new or deleted news entries

Example 2: Monitor E-commerce Product Prices

• URL: https://example.com/product/123
• Content Selector: Price (.price)
• Screenshot Selector: Product Details (.product-detail)
• Result: Monitor product price changes, record the time and range of price fluctuations

Example 3: Monitor Blog Article Updates

• URL: https://blog.example.com
• Content Selector: Article Content (article)
• Screenshot Selector: Main Content Area (main)
• Wait for Dynamic Content: 10 seconds
• Result: Monitor changes to blog article content, track article updates

Example 4: Custom Selector Monitoring

• URL: https://example.com
• Content Selector: Custom
• Custom CSS: .stock-status
• Result: Monitor content changes of custom elements (such as inventory status)

⬅️ Output

For your convenience, the output results are displayed in the form of tables and tabs. You can choose to download the results in JSON format.

Output Content Description

Each monitoring request will output the following data:

Basic Information

• url - Monitored web page URL
• currentTimestamp - Current timestamp

Content Comparison

• previousContent - Previous content (empty on the first run)
• currentContent - Current content
• changed - Whether changes are detected (true/false)

Run Status

• isFirstRun - Whether it is the first run (true/false)

Screenshot Data

• currentScreenshot - Current screenshot (Base64 encoded)
• previousScreenshot - Previous screenshot (if available)

JSON Example:

{
  "url": "https://news.ycombinator.com/",
  "previousContent": "Old headline...
Old headline 2...",
  "currentContent": "New headline...
New headline 2...",
  "currentTimestamp": "2026-04-15T10:00:00.000Z",
  "changed": true,
  "isFirstRun": false,
  "currentScreenshot": "Base64 encoded image..."
}

FAQ

How to monitor web page content changes?

1. First Run: Complete the initial configuration and run the task to get the baseline content
2. Run Periodically: Set up scheduled tasks to run the monitoring at a fixed frequency
3. View Results: Check the automatically generated change comparison results and screenshots

Recommendation: Use scheduled tasks (such as cron job) to run monitoring regularly.

How to choose the right selector?

Preset Selectors (Recommended for Beginners)

• Full Page Content (body) - Monitor the entire page text
• Page Title (h1) - Monitor changes to the main title
• Price (.price) - Monitor e-commerce product prices
• News Title (.titleline) - Monitor news lists

Custom Selectors (Suitable for Advanced Users)

1. Open the browser developer tools (press F12)
2. Right-click the target element you want to monitor
3. Select "Copy" → "Copy selector" in the right-click menu
4. Paste the copied content into the contentSelectorCustom input field

Recommendation: Try the preset selectors first, and use custom selectors only if they do not meet your needs.

How to set the monitoring frequency?

High Frequency (Hourly)

• Stock price monitoring
• Flash sale events
• Urgent inventory monitoring

Medium Frequency (3-5 times a day)

• News website updates
• E-commerce price monitoring
• Competitor analysis

Low Frequency (Once a day)

• Blog article updates
• Monthly report releases
• Product launch monitoring

Recommendation: Set the frequency reasonably according to the content update cycle, to avoid website access restrictions caused by excessive requests.

What is the function of screenshot comparison?

Screenshot comparison provides intuitive visual change detection, which can supplement the text comparison results and help you confirm the actual display changes of the page more clearly.

Recommendation: Do not set an overly large range for the screenshot selector, focus on the key monitoring area to reduce the file size.

What application scenarios is it suitable for?

• E-commerce Price Monitoring - Real-time monitoring of competitor price changes, and timely adjustment of your pricing strategy
• News Tracking - Track updates of news websites, and get the latest information as soon as possible
• Competitor Analysis - Monitor content changes of competitor websites, and keep abreast of market trends
• Inventory Monitoring - Monitor product inventory status, and realize timely replenishment
• Brand Monitoring - Monitor the display status of your brand on multiple platforms
• Government Announcement Monitoring - Real-time access to the latest updates of policies and regulations
• Recruitment Information Monitoring - Track new job postings on recruitment websites
• Social Media Monitoring - Monitor content changes of your social media posts