WatchParty is described as 'Watch videos together with friends. Chat and react in real time to a synchronized stream, with multiple ways of watching video, including screenshare, VM, and YouTube' and is an website in the Social & Communications category. There are more than 10 alternatives to WatchParty, not only websites but also apps for a variety of platforms, including Mac, Windows, Linux and Chrome OS. The best alternative is Metastream, which is both free and Open Source. Other great sites and apps similar to WatchParty are StreamParty (Freemium), Watch2Gether (Freemium), Hyperbeam (Freemium) and CyTube (Free, Open Source).
Metastream allows you to watch internet videos with friends. It synchronizes media on websites so you can watch together. Watch or listen together: Start a session and invite your friends by sharing your friend code with them.
Watch2Gether lets groups of users watch videos in-sync together. At the same time users can communicate through a build-in chat-room and use web cam and audio chat. Available media sources are Youtube, Vimeo, Dailymotion and Soundcloud.
Enjoy movie night online with your long-distance partner, start a watch party with good buddies, or hang out and binge anime with your best friend. Hyperbeam helps you stay close, even when you’re apart.
Invited.tv is a online video streaming service that allows friends to host watch parties using virtual browsers. Invited allows users to take turns controlling the virtual browser to easily browse and surf the web.
Host movie nights, listen to music or search the web. Bearcat has a chat, customization, different viewing modes, and you can give control to other users. Public rooms are completely free and all you have to do is make an account.