Drag a tab onto another tab or onto the page. A divider sets the width of each page.
Drag a tab onto another tab, hold it still for a moment, and the half it would take lights up. Let go and the two pages sit side by side. You can also drag a tab down onto the page and drop it on either half. You can also give Split View a key in Settings › Shortcuts.
A divider sets the width of each page. Drag it to any width. Double-click it to put it back at half.
While you drag, the divider snaps to 30/70, 40/60, 50/50, 60/40, and 70/30, with a light tap on the trackpad when it catches. Within 5 points of a split it stops there. Beyond that it follows the cursor again, so any other split is still reachable.
The active half has a border in your accent color. Each Space keeps its own pair. Choose Stop Split View to end it.
A web app stays in one window, so it has no Split View.
Satori is small, fast, and quiet, with one field for addresses and searches.
Download Satori for Mac.
Satori is signed with a Developer ID certificate and notarized by Apple. macOS may ask you to confirm the first time you open it, but there is no malware or unidentified-developer warning. Updates arrive on their own through Sparkle.