The 2.1 version of dotDefender for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The software relates to System Tools. According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software.
From the developer:
dotDefender is a software-based Web application firewall deployed as a Web server plug-in to identify and stop attacks that attempt to exploit vulnerabilities in Web applications.
dotDefender complements the network firewall and other network security products by intercepting seemingly legitimate users attempting to use the Web application to commit fraud, or gain access to valuable and confidential information.