A Chrome + Firefox extension to open the Slack app with its multi-workspace sidebar in a simple browser tab.

1. Install the extension from [the Chrome Webstore(pending)] or addons.mozilla.org
2. Visit app.slack.com and log into any of your workspaces
3. That's it, all your workspaces appear in the sidebar, just like in the Slack App

Under the hood, "Slack App-in-Tab" is a 10 LOCs long extension. It changes your browser's User Agent String to the one used in Chrome OS, when you visit app.slack.com. Slack always runs in app mode on that platform. Tada!

Note that this app cannot adopt WebExtension Manifest v3 until this chromium bug is fixed.

@louisremi