Here you can find some providers for developing your own app.
The App-Builder www.goodbarber.com impresses with beautiful graphical “themes”. They also offer some of the most advanced features like social networking, chat, geofencing and iBeacons.
A Progressive Web App (PWA, similar to a website on a mobile phone) costs about 25 Euro per month, native Android apps cost 48 Euro per month and iOS apps for Apple iPad and iPhone cost almost 100 Euro per month. There is also a Product Shopping App, a new builder for e-commerce apps.
If you want it to be completely free of charge, providers such as www.siberiancms.com, www.appsgeyser.com or www.mobincube.com are a good option. Even though the apps can be assembled without any programming knowledge, a certain basic IT understanding is helpful.