According to the Electronics Frontier Foundation (EFF) - one of the most prominent digital rights groups - some secure messaging apps offer more privacy against Big Brother intrusions and general surveillance than others. The organization has even rated them in a scorecard by various internal criteria, with only a few covering all requirements, including ones like "Is the code open to independent review?" or "Are past comm secure if your keys are stolen?" Insidermonkey experts made a list of 8 safest apps to send private and secure messages.
Out of the handful of secret messaging platforms that fulfill most requirements, an even lesser amount are what can be called user-friendly, meaning that they don't require an overly complex setup, and function largely like your everyday chat app of choice. Needless to say, the most popular ones like WhatsApp, Facebook Messenger, Viber, or Skype, are way down the list in terms of security, but there is a new generation of private messaging apps that offer both protection, and are suitable for daily drivers. You can also check our list of 9 iPhone and Android Secret Messaging Apps to Hide Text From a Girlfriend.