A change monitor takes a picture and a copy of a page, then compares the next check against it. When the difference is big enough to matter, you get a before and after rather than a notification that something moved.
What counts as a change
Two signals, and either can trip an alert:
- The text changed by enough to be meaningful rather than a stray character.
- The rendered pixels differ beyond a small threshold, which catches a layout or styling break that the words alone would miss.
Small edits fall under the threshold. That is deliberate, and it is the difference between a monitor you keep and one you mute within a week.
Clocks, countdowns and visitor counts do not count either. A spot that reads "Updated 12 minutes ago", "Sale ends in 02:59:41" or "27 people viewing" ticks on every visit, so those phrases are set aside before the comparison, and when nothing else changed the check stays quiet. A price, a percentage and an "only 3 left" are kept: they are the kind of thing a monitor is there to notice.
The first check never reports a change
The first check stores the baseline. There is nothing to compare it to yet, so it always passes. The check after it is the first that can report anything.
Watch a region, not the whole page
This is usually what you want. Pick the part of the page that matters in a live preview: a price, a stock message, a banner, a headline. Everything else can change freely without alerting you.
Simrix Monitor stores both the element you picked and where it sat on the page. If the site's markup changes underneath you, the monitor falls back to the saved position rather than going quiet, which is the usual way this kind of monitoring stops working without anyone noticing.
The picker also looks at the spot twice, a few seconds apart. If it changed on its own in that time, the way a slideshow or a rotating offer does, the picker says so before you save, because a monitor on a spot like that alerts on every check.
Ads and cookie banners are handled
Ad containers are hidden and cookie prompts dismissed before the page is captured, and the tool remembers which dismissal worked on which site so later checks get cleaner captures. Without that, a rotating ad slot alone would report a change on every single check.
Sensitivity
Three settings, chosen per monitor:
| Sensitivity | What it compares | Good for |
|---|---|---|
| Fast | Text only, unless the text has moved | Pages where wording is what matters |
| Balanced | Text and pixels | Most pages |
| Focused | Always compares the rendered image | Layout, styling and visual breakage |
Watching a page you do not own
This works on any publicly reachable page, which is how competitor watching works. Mark the site as a competitor or a watchlist site when you add it, and the label follows it through the app.
A page that requires signing in is out of reach, because checks never sign in.
What you get when something changes
A before and after you can drag between, a highlighted image of exactly which pixels differ, the text that was added and removed, and a short description of the change and how significant it appears.