Visual Diff Monitoring
Continuous screenshot baselines + pixel-level diff alerts. Catches silent layout regressions, DOM injection, hijacked CMS content — anything a synthetic uptime check misses.
How it works
- Add a Visual monitor in your dashboard — pick the URL + check interval (recommended 30 min).
- First check captures the baseline screenshot (1280×800, full page).
- Each subsequent check diffs the new capture against the previous baseline using ImageMagick.
- When the changed-pixel percentage exceeds your threshold (default 5%), an alert fires through every channel: email, Telegram, Slack, webhook.
What you catch
- Silent layout regressions after a deploy
- DOM injection via compromised third-party scripts
- Hijacked CMS content — text replaced, images swapped
- A/B test gone wrong — variant accidentally rolled out 100%
- Brand-asset drift on shared component libraries
Frequently Asked Questions
How often is each page captured?
Every 30 minutes by default; configurable per monitor down to the minimum your plan allows.
What counts as a "change"?
Anything above your pixel-diff threshold (default 5%). The 5% fuzz absorbs anti-aliasing noise; real layout/content changes always exceed it.
Are screenshots stored long-term?
Two PNGs per monitor — current + previous baseline + diff mask. Older snapshots roll off automatically.
Does this work on auth-walled pages?
Currently public pages only. Cookie/auth-aware capture is on the roadmap; until then point the monitor at a public preview URL.
Save & track URLs you check
Free account · 24/7 checks · alerts by email and Telegram — sign up to monitor any URL you test here.
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