1On one device, open More, then My loved songs, and tap Show a code.
2On the other, tap Enter a code and type it. It works once, for 10 minutes.
3That's it: one list everywhere. Love or remove a song on any device and all of them follow.
Works with the RadioActive app on iPhone and Android and with this web player on any computer. No account, no e-mail. Unlink any time, and that device keeps its own copy.