appSpotr is described as 'makes it possible for everyone to publish iOS and Android apps for free, without any knowledge of coding'. There are more than 10 alternatives to appSpotr, not only websites but also apps for a variety of platforms, including Android, Windows, Mac and iPhone. The best alternative is Android Studio, which is both free and Open Source. Other great sites and apps similar to appSpotr are Thunkable (Freemium), MIT App Inventor (Free, Open Source), AppConvertly.com (Paid) and AppyBuilder (Freemium).
Android Studio is the official integrated development environment (IDE) for Google's Android operating system, built on JetBrains' IntelliJ IDEA software and designed specifically for Android development.