The internet market is full of encrypted apps, but not all of them are reliable to use. After much research, it's possible to say that Signal is the best encryption app for iPhone. It's an instant messaging and video calling app that uses its advanced protocol for encrypting online communications. Besides this, the app has been audited, proving that it doesn't compromise users' security and privacy. However, as it's not very popular among the users, not a wide group of people use it. WhatsApp is the best alternative to Signal. It utilizes Signal protocol and standard AES-256-bit encryption to protect messages and calls. Also, it offers various security-boosting features that enhance the user experience.