Clock
Screensaver
Leave your Mac alone for a minute and it turns into a giant clock.
Open the file you downloaded, double-click ClockSaver.saver, click Install, then pick “Clock” under System Settings → Screen Saver.
A screensaver is the thing your Mac shows when you stop using it for a while. Most of them show photos or floating shapes. This one shows the time, and nothing else.
The screen goes black and the clock takes over all of it: hours, minutes and seconds in enormous white letters, set in Anton — the same chunky font as the big headlines on this site. The seconds sit inside a red block, so they look like a word you have selected with your mouse. The numbers stretch to fit whatever screen they land on, from a small laptop to a huge monitor, and always leave a neat margin around the edge.
It also redraws the picture only when the time actually changes — once a second, instead of sixty times a second like most animations. So it sits there quietly and barely touches the battery.
It is written in Swift, the language Apple uses for its own apps, and the font is packed inside the file itself. That way it looks right on any Mac, even one that has never had that font installed.
The fiddly part is getting it onto someone else’s Mac at all. macOS does not trust files that come off the internet, and normally puts a warning in the way. So the studio wrote one script that does the whole job in a single run: build the screensaver, sign it with the studio’s Apple developer key, pack it into a disk image, send it to Apple to be checked — that check is called notarising — and then staple Apple’s approval onto the file. Because the approval is stapled on rather than looked up online, your Mac can see it even with the Wi-Fi switched off.
What comes out the other end is the download on this page. Open it, double-click, install, and it just works — no warnings, no fixing settings afterwards. Free, and about the size of one photo.