Trustwave SecureBrowsing is a free, browser-based security plug-in

Only the Trustwave SecureBrowsing plug-in uses real-time security technology to scan and analyze the code of a proposed web page, every time a URL link appears. Others check with static lists or use a website’s reputation to determine if a proposed link is safe to follow. Using a static list is ineffective because the content on the most-visited websites, such as LinkedIn and Facebook, is changing constantly. Therefore the website code changes, and this makes static approval lists quickly outdated. Other vendors use reputation which is an even less valid option since the majority of attacks are on legitimate websites that would show up as “safe” based on reputation. https://www.trustwave.com/securebrowsing/faq.php