The Prisoner's Keyboard is the first iOS keyboard built for creative writing.
Based on the Prisoner's Constraint, an Oulipian writing game, the Prisoner's Keyboard lets you remove particular letters from appearing at all.
This empowers you to create lipograms, writing in which a particular letter or group of letters is avoided. For a classic example of lipograms in action, check out Christian Bök's Eunoia.
The Prisoner's Keyboard does not collect any information about you and doesn't have the ability to record what you type.
The Prisoner's Keyboard is a poems.io joint and made with love by Nick Barr.