Safe browsing is a feature that warns you when you are about to visit a dangerous site known for malware, phishing and downloading unwanted software on your device.
How does safe browsing work?
Firefox Klar has been using the Google safe browsing API for Safe browsing. When you click a link, we check the link against lists of reported phishing, unwanted software, and malware sites. If the site is identified as an attack site, Firefox Klar (versions 6 and older) will warn you against visiting it.