Airmac is described as 'free application what turns you Macintosh into an Airplay receiver'. There are four alternatives to Airmac for a variety of platforms, including Mac, Windows, Xbox, Android and iPad. The best alternative is AirServer. Other great apps like Airmac are AirParrot (Paid), Reflector (Paid) and X-Mirage (Paid).
Reflector is an AirPlay receiver that allows you to wirelessly display your phone or tablet on a number of devices. It’s available for Mac, PC and most Android devices. Mirror your device on a big screen without wires or complicated setups.