Vidar is described as 'Open-source end-to-end encrypted SMS application utilizing the Advanced Encryption Standard (AES256) to send symmetrically encrypted messages. Unlike most messaging apps, Vidar operates entirely over SMS; this eliminates the need for internet access or external' and is a instant messenger in the security & privacy category. There are more than 25 alternatives to Vidar for a variety of platforms, including Android, Android Tablet, F-Droid, Web-based and iPhone apps. The best Vidar alternative is Fossify Messages, which is both free and Open Source. Other great apps like Vidar are QUIK, QKSMS, Right Messages and Google Messages.