In our tests, Immunet detected and removed threats more effectively than any other solution. It is based on Clamwin, the Windows port of renowned open-source antivirus ClamAV. Immunet is a free AV for Windows Server that utilizes real-time cloud analytics drawn from millions of end-users to provide cutting edge virus detection. We have installed and tested each one to ensure they are compatible with Windows Server. Below are our picks of the top free anti-virus programs for Windows Server editions. We recommend running an anti-virus/anti-malware application on all Windows machines, with Windows servers no exception.