Pre-releases are early builds of VisualDiffer, published to test new features and bug fixes before they reach a stable version. They are signed and notarized by Apple like every other release, but they may still contain bugs.

Install

Open the releases page and look for a build marked Pre-release; its version number ends with alpha or beta.
Download the VisualDiffer-<version>.zip file from the Assets section of that release.
Unzip it wherever you want, there is no need to copy it to the Applications folder.
There is no need to uninstall the version you already have.
Launch it and try it.
Once you are done, you can delete it.

Good to know

macOS asks you to confirm the first launch because the app was downloaded from the internet. No security warning is shown, the app is notarized by Apple.
A pre-release is never listed as the Latest release and is never offered by the in-app update check, so the version you already have installed keeps updating to stable releases only.
A pre-release does not check for updates on its own: to get a newer build, come back to the releases page and download it again.

Report a problem

If something goes wrong, open an issue on GitHub and include the version number shown in the About window.