VirusTotal Browser Extension.
Avoid infections and other unwanted outcomes when you receive a suspicious file or link by checking the file or link with VirusTotal’s free and easy service. VirusTotal's mission is to help make the internet a safer place while helping to improve the security and antivirus industries and the online safety of other members of the VirusTotal Community. Learn more at https://support.virustotal.com/hc/en-us/articles/115002126889-How-it-works.
By default the extension also allows you to collaborate with the security industry by sharing the DNS resolutions (ip address to domain name mappings) performed by your browser. These will never be tied to your identity and the sharing can be deactivated in the extension settings.
Virustotal is a free online service that analyzes files and URLs enabling the identification of viruses, worms, trojans and other kinds of malicious content detected by antivirus engines and website scanners. VirusTotal is not a substitute for antivirus or security products, but integrates over 60 antivirus solutions and more than 60 URL scanning tools to provide a valuable second opinion on a given file or web site and as a way to detect false positives.