- Apache Cordova is a community project, letting you build mobile apps for various mobile platforms with one unique code base, as you develop your app with web technologies (HTML5, Javascript and CSS3) instead of relying on platform-specific (native) APIs like those of Android, iOS, or Windows Phone.
- Phonegap is a version of Cordova but it’s an Adobe product.
- Ionic Framework is a set of css classes and a library of Javascript directives and modules, built on top of Cordova, with AngularJS.
Here is an extract from Apache Cordova Wikipedia page, but that is true for PhoneGap and Ionic as well:
The resulting applications are said to be hybrid, meaning that they are neither truly native mobile application (because all layout rendering is done via Web views instead of the platform’s native UI framework) nor purely Web-based (because they are not just Web apps, but are packaged as apps for distribution and have access to native device APIs).
All three projects are free and open-source.