Telegram. Which does need a number for registration. However you can add an password and don't need to use the number ever again after sign-up, so I can safely

Telegram. Which does need a number for registration. However you can add an password and don't need to use the number ever again after sign-up, so I can safely use throwaway numbers without getting locked out or hacked. Also people can't randomly find me there because of proper privacy settings.