ifttt - IFTTT puts the internet to work for you. Create simple connections between the products you use every day.
Future Me - Send an email to your future self
Mycroft.AI - Mycroft is the world’s first open source assistant.
Dabble Me - Your own private place to write. A journal/diary to help you remember what's happened in your life.
Google Assistant - Get things done with Google Assistant
Letter to Yourself - Send a physical letter to your future self