The following platforms are currently supported:
- Mac OS X / PowerPC
- Mac OS X / x86 (via Universal binary)
- Mac OS 8.5-9.2.2 / PowerPC
- Mac OS 7.6.1-9.2.2 / PowerPC (only version 2.9.9a)
- System 7.1-8.1 / 68k (only version 2.9.9b)
All of these are available for free download. However, some "Pro" features are available only for registered (paying) users. iCab is one of very few browsers being developed for Mac OS 9 and earlier versions of System Software, and is the only one available for 68k systems that features tabbed browsing. At the same time, it is compatible with the latest hardware and system software.
iCab's proprietary rendering engine has often been criticised for not supporting CSS and DOM, making it hard to design modern Web pages for the browser. However, in May 2005 the first public beta of iCab 3 was released with dramatically updated layout capabilities (including CSS2 support), although this version is not available for 680x0-based Macs. The iCab 3 series also has proper Unicode support, using ATSUI instead of the old WorldScript; this is the reason behind iCab 3 requiring Mac OS 8.5 or later.
One interesting feature of iCab is the iCab-Smiley. Depending on the validity of the HTML of the web site currently viewed, it will smile or frown. Clicking on the smiley will bring up a list of any errors on the page, while shift-clicking it will activate an easter egg. This feature was first seen in the same author's earlier web browser, CAB, for Atari TOS compatible computers. CAB is an acronym for 'Crystal Atari Browser' and was one of the few browsers available for the platform.
- Tabbed browsing.
- Multiple language support, including Arabic on older Macs (cannot display UTF-16 pages).
- Sophisticated filtering out of images and plug-in content (e.g. ads).
- Kiosk mode: full-screen display and access controls.
- Download manager:
- Allows the user start, stop, resume and review downloads.
- Maintains a download history.
- Supports downloading one page or a whole site (crawling) with many configuration options.
- Portable web archives: ability to save pages as a ZIP archive containing HTML and images.
- Acid2 test compliance.
- Highly configurable print dialog.
- History window which can sort by title, last access date, or URL
- Hotlist (bookmark) mechanism which can automatically or manually check for updates to bookmarked sites.
- Reload a single image on a page without needing to reload the whole page.
- Disable web "annoyances" such as animated GIFs and embedded sound files.
- Pretending to be another browser.
- Support for sessions (i.e. saving and then loading all open windows and tabs).
- Adding any query (e.g., search engine, Wikipedia) to the toolbar search widget by point-and-click.
iCab attracts criticism for:
- Worse performance than the Gecko and WebCore-based browsers.
- Instability, relative to its competitors.
- A perceived lack of interface polish (i.e. overcrowding of features).