iCab is a web browser for the Macintosh by Alexander Clauss, derived from Crystal Atari Browser (CAB) for Atari TOS compatible computers. It is the most recently actively developed browser for 68k-based Macintoshes that features tabbed browsing and one of a very few browsers that was still updated in the recent past for the classic Mac OS at all; only Classilla is more recent. The downloadable product is fully functional, but is nagware—periodically displaying a dialog box asking the user to register the product, and upgrade to the "Pro" version.