Spure (try it here) is an ultra-minimalistic text editor. Not only that it doesn't let you edit what you have written, but it also hides it from you almost completely.
Previously I have prototyped it in Racket.
Write your text in the text box. Except for corrections in the current word, you cannot make any changes!
When you're done, click the Spure button. Your text will be displayed. You can save it and reset the app.
The deployed app is free for use. I currently work on this as a personal project without contributions and therefore don't release it under a license. This may change in the future.