OnyX is a free maintenance program for macOS from Titanium Software. It clears caches, runs the maintenance scripts Apple already ships, rebuilds indexes, and exposes preferences that the System Settings app hides. A new build appears for each major macOS version. Use the one that matches the system you are on. The old one will refuse, and that is correct.
It is not open source. The parameters screen can change behavior you will not notice until an app looks wrong. Do not flip undocumented toggles from a screenshot. OnyX is housecleaning. It is not a privacy suite, and it will not remove an iCloud backup you already made.
Use it when a Mac is sluggish and you want one window instead of ten terminal commands. titanium-software.fr
Match OnyX to the macOS version. Run the cleaning tasks, not the parameter experiments, unless you can undo them. It will not uninstall iCloud, and it will not stop a backup to Apple if you left that on. Smart folders and Spotlight rebuilds can make the Mac busy for an hour. That is not a crash. Freeware from a long-running Mac developer is still freeware. Download it from Titanium’s site, not a mirror.
