Screenshots & Visual Diffs

4 min read

See exactly what changed with viewport screenshots captured on every check and pixel-level visual diffs. Available on the Pro plan.

Pro feature: Screenshots and visual diffs are available on the Pro plan. Free users see a "Visual screenshots available on Pro" message.

What Screenshots Capture

On every monitoring check, CheckSite captures a viewport screenshot of the monitored page in WebP format. This gives you a visual record of what the page looked like at each check, so you can see changes with your own eyes rather than relying solely on text-based analysis.

Before capturing, CheckSite freezes CSS animations on the page to ensure a clean, stable image. The screenshot is saved as the monitor's latest state and is overwritten on each subsequent check.

Before/After Comparison

When a change is detected, CheckSite automatically saves a pair of screenshots:

  • Before — what the page looked like before the change (copied from the previous check's latest screenshot)
  • After — what the page looks like now, captured during the current check

This pair is stored alongside the change record so you can always go back and see exactly what was different.

Visual Diff

In addition to the before/after screenshots, CheckSite generates a pixel-level visual diff that highlights exactly which parts of the page changed. Areas that differ between the two screenshots are highlighted in red, making it easy to spot changes at a glance — even subtle ones like a font size adjustment or a shifted element.

Tip: The visual diff is especially useful for design-heavy pages where text-based change detection might not capture layout shifts, color changes, or image swaps.

Viewing Screenshots

To view screenshots for a monitor:

  1. Go to the monitor detail page
  2. Open the change you want to inspect in the change history
  3. Click the Screenshots button to view the before/after images and visual diff

Click any screenshot to open it in a full-size lightbox. Press Esc or click outside the image to close the lightbox.

Retention & Storage

Screenshots are stored securely in private cloud storage. Key details:

  • 30-day retention — screenshots older than 30 days are automatically cleaned up by a daily maintenance job
  • Latest screenshot — always available for each monitor, showing the most recent check's capture
  • Change pairs — before/after screenshots are linked to their corresponding change record

Non-Blocking Capture

Screenshot capture is designed to never interfere with monitoring. If a screenshot fails to capture for any reason — network issues, page rendering problems, or storage errors — the monitoring check continues normally. You will still receive change notifications and text-based analysis. Screenshots are a visual supplement, not a dependency.