Codogram is a communicative tool that requires no sign up and allows you to create messages that can be sent right away, but will only open up in future (you decide when, but once a message is made- it can't be changed).
Codogram allows you to create and send encrypted messages to make predictions, postponed confessions, letters to your future self etc.
For example, when watching a movie with friend you can create a message like "I knew the janitor was the murderer", set the opening time for an hour later and send the code to your friend - you won't spoil the movie for your friend, because you set the opening time for after the movie, but at the same time you'll show your friend, that you knew the ending. See more examples on what to use Codogram for at codogram.com.
Codogram: They'll know when you want them to.