Software @ Berkeley is a consolidation of several IST sites that offer software to UC Berkeley faculty, staff and students for free. Software downloading requires a CalNet username and passphrase. Software available for free to students through Software @ Berkeley includes:
You can see a full list of all campus-provided software that you are eligible for here.
Most new computers come with antivirus software that keeps itself up-to-date for a trial period, after which you must purchase an ongoing subscription. Microsoft, however, provides free antivirus software to Windows users. For all active/current versions of Windows, this software is called Windows Security and it comes installed on your computer. We recommend using this free, easy-to-use option for antivirus software, but the most important thing is that you are using antivirus software that is active and up-to-date. Using an antivirus program that has expired means your computer is not being protected!
Make sure you uninstall any other antivirus software that may be installed on your computer before (re-)activating Microsoft's software. Having more than one antivirus package installed/running can cause problems that may be difficult to fix. If you previously used a different brand of antivirus software (which expired or which you uninstalled), you should always double-check that Windows Security has "taken over" and is actively protecting your computer again after you remove it, as other security software will sometimes deactivate Windows Security automatically.
Mac viruses are still very uncommon and antivirus software is generally not a necessity for Mac users (unless they are running Windows on their Macs). Berkeley no longer offers free antivirus software for Macs, and the campus policy is that the built-in security features of MacOS are sufficient. If you believe you've accidentally installed malware on your Mac, a good free malware scan app is MalwareBytes (there is no need to use the paid version).