modernize legacy systems or construct scalable internal or customer-facing apps in the right time to market, then I advise you to jump to my cross-platform mobile development guide for enterprises right away.
It includes open-source and free cross-platform mobile app development tools that any developer can use instantly.
Apache Cordova

Apache Cordova is first on this list because it powers the construction process for most free cross-platform mobile application development tools, and many that aren't free, for that matter. Formerly known as Phone Gap, Adobe released Cordova as an open-source project which, as of this writing, has received contributions from BlackBerry, Google, IBM, Intel and Microsoft.

By wrapping web code in a native Cordova package, Cordova can offer access to native APIs. And by incorporating community-built plugins, apps can connect to any number of those APIs using plain JavaScript.

Cutting out the middleman. By working directly on top of Cordova, developers have access to the latest updates from Apache’s team. With each version, Cordova gains access to critical OS enhancements. These enhancements may improve Cordova’s performance and provide it with access to new APIs. Build right on top of Cordova and you’ll never miss out.

Cordova is UI and framework-agnostic. It leaves all the design and architecture decisions to the developer. This may not be an issue if you’ve built mobile-first websites before. But if this is your first time working on a mobile application, consider a framework that does a bit more hand-holding. And according to Stack Overflow’s developer survey, developers dread working with Cordova above all others.