The best open source alternative to join.me is Jitsi, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to join.me and 17 is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to join.me are DWService (Free, Open Source), UltraVNC (Free, Open Source), TigerVNC (Free, Open Source) and Remotely (Free, Open Source).
Jitsi (previously SIP Communicator) is an audio/video and chat communicator with full encryption that supports protocols such as SIP, XMPP/Jabber, ICQ/AIM, Windows Live, Yahoo!, GTalk/Hangouts extensions, as well as OTR, ZRTP, etc.
DWService is an open source project which offers a service that allows access to remote systems (Windows, Mac, Linux, Raspberry...) using a standard web browser - without any component required on the client side.
UltraVNC is easy to use and free software that can display the screen of another computer (via the Internet or a local network) on your own screen. The program allows you to use your mouse and keyboard to control the other computer remotely.
TigerVNC is an advanced VNC implementation. It is based on the fourth generation of VNC. TigerVNC also includes features from the TightVNC and TurboVNC projects. This includes accelerated JPEG compression. TigerVNC supports the latest X.Org X server.
Dayon! is a user friendly, open-source, cross-platform solution, that allows controlling of remote computers. It can be used as free alternative to various commercial remote desktop and remote assistance products.
A VNC/SSH Client for the GNOME Desktop - You can connect to several machines at the same time with tabs - You can keep track of your most used connections with favorites - You can keep track of your recently used connections through GtkRecent - You can browse your...