Tasker - Tasker is an application for Android which performs Tasks (sets of Actions) based on Contexts...
Kodular - Much more than a modern app creator without coding
AutomateIt - Automate Your Android!
Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
Automate - Automate various tasks on your Android smartphone or tablet.
MIT App Inventor - App Inventor is a cloud-based tool, which means you can create apps for phones or tablets right in your web browser.