title_body: How to convert jarirreader format to PDF/Mobi I do have a book extension is .jarirreader from https://jarirreader.com/
  
  However I can't read / convert the book unless i open it with there app. 
  here is the book structure. 
  
  
  Images contains the cover / index has Json format / Text has chapters with HTML extension.
upvoted_answer: It's most likely a custom format with DRMed and/or obfuscated files. Try opening the files in the text folder with a web browser. If you can read them in a browser you can re-assemble them to a book with an epub editor.