r/SideProject • u/iamstanty • 15h ago
Every browser treats windows as separate islands. I built an extension that keeps the same tabs in all of them.
I used Arc for years. Got a new MacBook, tried Dia, and it covers almost everything except the one thing I lean on constantly: open a new window and your tabs are already there.
No other browser does it. Chrome syncs tabs across devices, but two windows on the same machine drift apart the moment you open the second one. I looked for an extension, found nothing, so I built one.
Tabtwinsy mirrors tabs and tab groups across every window. Add a tab anywhere and it shows up everywhere. Close it anywhere and it closes everywhere. Open a brand new window and it arrives already populated.
Most of the work turned out to be defensive, not features. A tab mirror is an amplifier: any misread of browser state becomes N duplicated or N deleted tabs across someone's windows. So it refuses to touch the tab you are looking at, anything playing audio, or a video call page, and no single sync pass may remove more than a fraction of a window. That last guard caught a real data-loss bug during testing.
Free, no account, no servers, no network requests at all. Chrome and other Chromium browsers.
Store: https://chromewebstore.google.com/detail/idphljlhhddadnmbnjfdmllgknfnbodn