What it does
Visual regression catches an unintended UI change that a functional test would pass straight through: a shifted button, a broken layout, a colour that changed by mistake. You take a baseline of a page you are happy with, and every later comparison tells you whether the page still looks the same and, if not, precisely where it differs.
Capture a baseline, then compare
- Enter the URL and capture a baseline. A headless Chromium browser loads the page and takes a full-page screenshot, which is stored for you.
- Later, compare a live URL against that baseline. The platform loads the page again and runs a pixel-level comparison against the stored image.
- Read the result: a diff percentage, a pass or fail against your threshold, and a diff image with the changed pixels highlighted.
Element drift, not just pixels
The UI and UX testing tab works at the DOM level. It captures elements on the page, matches them against the last baseline, keeps a rolling history of the last few states per element, and runs a rules-based audit. This catches a change to an element that a whole-page pixel diff might average away.
Mask the parts that always change
A page with an ad slot, a carousel or a live clock would fail a naive pixel diff every time. When you capture a baseline you can set the viewport size, the comparison threshold, a selector to wait for before the shot, and ignore regions that mask the areas you expect to change. That keeps a comparison meaningful instead of noisy.
What it does not do today
- It is Chromium only. There is no true cross-browser visual diffing against Firefox or WebKit yet, so do not rely on it to catch a rendering difference that is specific to another engine.
- There are no per-dimension AI scores. An earlier build showed fabricated semantic, layout and colour scores; those were removed. The only score is derived from the real pixel difference.
- A comparison needs a baseline first. It is a capture-then-compare workflow, not a one-shot compare of two arbitrary URLs.
Questions people ask about this
- Can it diff across browsers?
- Not today. Capture and comparison run in Chromium only. Cross-browser visual diffing is not available, so a guide or a claim that implied it would be wrong.
- Is it on the Free plan?
- No. Visual regression is included on Solo Pro, Team and Enterprise. The Free plan does not include it.
Source: /documentation/visual-regression, updated 2026-09-18. Answers are checked against the shipped product on that date.
Found something out of date? The people who build the module answer the contact form on the home page, and corrections to this guide are dated above. Tell us.