Kaizu
Swift and WebKit
A quiet web browser for the Mac, built natively on the engine behind Safari. The name means sea chart.
Open source. Test version out now.
The idea.
Browsers are where most of the day goes, and most of them feel like it. We wanted vertical tabs and a command bar without giving up what a Mac app should be: fast, native and light on the battery.
So Kaizu is written in Swift on WebKit, the engine behind Safari. No Chromium underneath, and nothing between you and the page.
What we built.
Sidebar.
Spaces, favorites, pinned tabs and folders, and Today tabs that archive themselves.
Command bar.
Addresses, open tabs, history and every menu command in one place, plus sums and conversions.
Real profiles.
Each profile keeps its website data fully isolated.
Privacy built in.
Ads and trackers blocked, cookie pop-ups rejected, tracking parameters stripped.
Light on the Mac.
Idle tabs hibernate and wake exactly where you left them.
Extensions.
Installs from the Chrome Web Store and Firefox Add-ons.
Four days, first commit to here.
98 commits and about 11,800 lines of Swift, from October 25 to October 28, 2026. That's what rapid software prototyping looks like when the idea is clear.