Zener Cards are a classic extra sensory perception (ESP) experiment testing for telepathy. 2 people are required. Paid App: Set the number of cards in a test, records your results as sender and receiver, and even has a Ghostbusters Mode! With quotes from the film the Sender can say during the test. Free App: A basic 10 card Zener ESP test. Everything you need to do this classic ESP test with a friend. 16th Century doom-sayer and prophet Nostradamus did not use any other software! And that's a fact.