Onyx is a free system maintenance tool for Mac OS X.
One of the nice things about Onyx is that it covers everything you can think of. It’s packed with tools that you might want to use often, plus some you might use only once in a blue moon. But they’re all there, in one place.
What sort of tools? Stuff that checks and verifies your disks, stuff that cleans up caches and other non-essential files, stuff for rebuilding and looking after system files that need a bit of TLC.
Onyx goes to great lengths to look after you. It’s a powerful tool, so it asks for an administrator password before running certain tasks. It also flashes up several warnings, and a Help Viewer page, so that you’re left in no doubt about the potential consequences of your actions.
Don’t let that serious-sounding stuff put you off though. Onyx is simply a useful thing to have around, it’s free as in yay! free!, and it deserves a place in your Applications folder.