What are some alternatives?
When comparing Lianja App Builder and Siberian CMS, you can also consider the following products
OpenXava - OpenXava is a Web Java Framework for Rapid Development of Enterprise Applications.
Fuse - Fuse is a UX tool suite for mobile app designers and developers.
Microsoft PowerApps - Microsoft PowerApps provides tools to create, customize, share and run apps.
Dropsource - Mobile development platform for building native iOS & Android apps
GoodBarber - GoodBarber is a mobile app creation platform.