VoltBuilder is described as 'A modern replacement for PhoneGap'. There are three alternatives to VoltBuilder for a variety of platforms, including Linux, Mac, Windows, Android and iPhone. The best alternative is Ionic Framework, which is both free and Open Source. Other great apps like VoltBuilder are Monaca (Freemium) and Capacitor by Ionic (Free, Open Source).
Monaca makes the hybrid mobile app development process with PhoneGap/Cordova simpler and stress-free with our comprehensive cloud-powered app development tools and services. Monaca can easily be plugged into your existing workflow.
Capacitor is a cross-platform app runtime that makes it easy to build web apps that run natively on iOS, Android, and the web. We call these apps "Native Progressive Web Apps" and they represent the next evolution beyond Hybrid apps.