Natural Syntax

An advanced ePub reader with lexical highlighting for your iPad and iPhone.


As programmers read source code we passively absorb some of the meaning via syntax highlighting for the language. NaturalSyntax aims to do the same thing with natural human language, this will improve reading comprehension and understanding by passively absorbing the parts of speech via subtle styling of the text.


  • Works on iPhone and iPad devices
  • Color codes parts of speech in ePub files
  • Includes discovery service to download thousands of public domain books
  • Allows customization of colors and styles for each part of speech
  • Includes Dark, Light and White themes with different default colors
  • Allows you to turn on or off highlighting of each part of speech
  • Synchronizes preferences between all your devices
  • Uses system interface for interacting with your files
  • Does not collect or store any personal information


  • Can only process English ePub files
  • Can only search for public domain books when signed into iCloud