Cross-Browser Support
The Visual Editor is a browser extension called AvsB Dev Tools. It's built for Chrome, Firefox, and Edge from one codebase. Other Chromium-based browsers, like Brave or Arc, can run the same Chrome build too.
A variation is one version of your page: the control, or one of the challengers you're testing against it. Building and editing a variation needs the extension. Nothing about running your test does: your visitors never install anything, in any browser.
None of the three browser stores has a public listing today. Chrome's listing exists but is still in review, and Firefox and Edge have no listing at all. Until one goes live, every browser installs the same way: download the extension and load it yourself, using the steps below.
Google Chrome and Edge
Chrome and Edge share the same build, since Edge runs on the same engine as Chrome.
Download the extension
Download the extension (.zip) and unzip it into a folder you won't accidentally delete.
Open your browser's extensions page
Go to chrome://extensions in Chrome, edge://extensions in Edge, or the matching address in another Chromium browser (brave://extensions, and so on).
Turn on developer mode
Toggle Developer mode on, in the top-right corner. New buttons appear above the extension list.
Load the unpacked extension
Click Load unpacked and select the folder you unzipped. The extension installs right away, and the AvsB icon appears in your toolbar.
Pin and sign in
Pin the extension to your toolbar, click the icon, and sign in with your A vs B account. You're ready to edit.
A store install updates itself in the background. This kind of install does not: download a new zip and repeat Load unpacked whenever a new version ships. Once Chrome's listing goes live, that install will update on its own and this page will link to it directly.
If the AvsB team has already sent you Chrome's direct Web Store link, it installs the extension normally, ahead of the public listing.
Mozilla Firefox
Firefox needs its own build (its extension format differs from Chrome's), so use the Firefox-specific download.
Download the Firefox build
Download the Firefox build (.zip) and unzip it into a folder you won't accidentally delete.
Open Firefox's temporary add-on loader
Go to about:debugging#/runtime/this-firefox.
Load the extension
Click Load Temporary Add-on and select the manifest.json file inside the folder you unzipped.
A temporary add-on stays active only until you close Firefox. Repeat the steps above each time you restart the browser.
Unsupported browsers
Safari has no AvsB Dev Tools build today. You can still preview a variation on Safari with a preview link: only building one needs Chrome, Firefox, or Edge.
The extension is only for the person building a test. The separate A vs B snippet is what shows the finished variation to your visitors, and it runs on a much wider set of browsers: Chrome 80+, Safari 13.1+, Firefox 74+, and Edge 80+, all from 2020 or later. On anything older, the snippet just doesn't run. The visitor sees your normal page, control and all, with no error and nothing broken.