Install the extension

Add SmashSSO to your Chrome.

The extension is what carries out your changes, in your own browser. It takes about two minutes to install by hand, in six steps.

Chrome 120 or newer, on Mac, Windows or Linux.

1
Download the extension
One small zip file. It lands in your Downloads folder.
It is the same extension for every company; pairing, in the last step, is what ties it to yours.
2
Unzip it and put the folder somewhere it can stay
Double-click the zip. You get a folder called smashsso-extension. Move it out of Downloads, for example to Documents.
Chrome runs the extension from this folder every time it starts. If the folder is moved or deleted, the extension stops working.
3
Open Chrome's extensions page
Type chrome://extensions in the address bar and press Enter.
Chrome does not let a web page open that address for you, which is why this one is typed.
4
Turn on Developer mode
It is the switch in the top right corner of that page. New buttons appear along the top.
Developer mode is how Chrome installs an extension from a folder. It changes nothing about your other extensions.
5
Press Load unpacked and choose the folder
Pick the smashsso-extension folder itself, the one with manifest.json inside. SmashSSO appears in the list.
Pin it from the puzzle-piece menu in the toolbar if you would like its icon in view.
6
Pair this browser
Open SmashSSO, go to Settings, and press Pair this browser. That is the whole setup.
From then on, changes you request run in this Chrome, in a tab group named SmashSSO.

Good to know

After it is in.

Chrome mentions developer mode: Chrome may remind you that an extension is running in developer mode. That is expected for one installed from a folder; keep it.
Updating: Download the new zip, replace what is in the smashsso-extension folder with it, and press the reload arrow on the SmashSSO card at chrome://extensions. The folder stays where it is, so the browser stays paired.
Removing: Press Remove on the SmashSSO card at chrome://extensions, and unpair the browser in Settings. Queued changes then wait for another paired browser.
What it can do: It acts in tabs it opens itself, for changes you asked for. The security page says exactly what it may and may not touch.