AVG has added security software for Apple's Mac operating system to its range of products for Microsoft Windows, Linux and Unix-based FreeBSD.
LinkScanner for Mac is the first AVG product designed for Mac OS X Leopard or Snow Leopard that is available for free download.
The product also supports the Apple's Safari internet browser versions 3 to 5 and Mozilla's Firefox 3 and higher.
"Mac users have traditionally been less vulnerable to attacks because of their lower market share, but that is quickly changing," said JR Smith, chief executive at AVG Technologies.
No operating system is immune as attacks are increasingly using legitimate websites to deliver malware that targets web browser and application vulnerabilities, he said.
Some 99% of all malicious threats are delivered through the web and cannot be stopped with traditional anti-virus software, AVG research has shown.
"Because AVG believes strongly that security software like LinkScanner is critical, we believe it should be free," said Smith.