It depends on what kind of app you are looking to develop and what your skill set is. These days there are a lot of DIY app builders that let you build basic apps. If what you are looking for is one of the features offered by the app builders then you are in luck. Otherwise, if you have some coding skills, many app builders let you add your own code as a plugin too. All the ones I am listing below will let you do that.
GoodBarber | Create apps with the best app builder for iOS and Android (You can add login feature on Goodbarber apps)
Build Native iPhone APPS
Create Android apps without coding using Andromo App Maker for Android
and for hybrid apps with HTML and CSS
Ionic Builder Home
are couple good places to get you started
Here is a little more detailed information from a post I did some time back about some of these app builders : 6 Mobile App Builders you can use to build Apps without Programming -