GetStream.io - APIs for the development of scalable newsfeeds and chat applications.
Letter to Yourself - Send a physical letter to your future self
Mini Diary - Simple and secure journal app
Future Me - Send an email to your future self
Jarme - Journaling made fun again
Letter to my future self - Letter to my future self is a prominent email scheduling service that gives you the opportunity to create a letter with goals and thoughts for your future self and schedule a date for sending it.