VTzilla and VTchromizer are Firefox and Chrome add-ons which simplify this process by integrating VirusTotal scanning options into the browser, enabling you to check any file or URL with one or two clicks.
If you’re unsure about a particular link, for example, you can right-click it and select “Scan with VirusTotal”. This immediately runs a regular VirusTotal URL check, and displays a detailed safety report in just a few seconds.
A normally safe site might occasionally host something dangerous, of course, and both VTzilla and VTchromizer add an addition “Scan with VirusTotal” option to the right-click menu for a download.
VTzilla then goes one step further by adding a “Scan with VirusTotal” button to the Firefox download box. This is good, as it acts as a permanent reminder to be careful about what you’re downloading, and enables you to run a scan with just one click. But it’s also more intrusive, and may not appeal to everyone.
VTzilla takes a similar, more “in your face” approach elsewhere. In particular it adds a toolbar where you can search VirusTotal for hashes, URLs and more, or launch a scan of your current site; this works, but it takes a lot of screen real estate and isn’t customizable (although you can at least turn it off). Meanwhile VTchromizer is more subtle. It only adds a single button to the Chrome toolbar, but this still gives access to a VirusTotal search box and a “Scan current site” link.
VTchromizer would be our preferred extension, then, but VTzilla is also useful, and both add-ons make it easier to check downloads for malware on demand.