Free and simple. There aren't too many ads and it works well, definitely worth a try!
Quick Touch - Automatic Clicker is a mobile application that will click or swipe any location on your smartphone screen so that you can keep certain functions or actions active without having to worry.
With this app, you can indicate exactly where on the screen you want to be clicked and how often or at what frequency. It can be incredibly useful for example when playing certain games that require repetitive touches in one spot, as fast as possible.
You can schedule the exact time you want the click to begin and end, or program its duration. You can also save your settings. Quick Touch has multiple possibilities, making it ideal for gaming and is completely free.