Virustotal.com is a free online antivirus to help you determine if a certain file or a website has a virus.
VirusTotal aggregates many antivirus products and online scan engines to check for viruses that the user’s own antivirus may have missed, or to verify against any false positives. Files up to 650 MB can be uploaded to the website, or sent via email (max. 32MB). Anti-virus software vendors can receive copies of files that were flagged by other scans but passed by their own engine, to help improve their software and, by extension, VirusTotal’s own capability. Users can also scan suspect URLs and search through the VirusTotal dataset. VirusTotal for dynamic analysis of malware uses the Cuckoo sandbox. – Wikipedia