Tasker - Tasker is an application for Android which performs Tasks (sets of Actions) based on Contexts...
ifttt - IFTTT puts the internet to work for you. Create simple connections between the products you use every day.
AutomateIt - Automate Your Android!
Mycroft.AI - Mycroft is the world’s first open source assistant.
Automate - Automate various tasks on your Android smartphone or tablet.
Google Assistant - Get things done with Google Assistant