Is there a money-back guarantee?

Yes, the Build-a-Book Guarantee. If the studio is not what you expected, write to support within 14 days of your purchase for a full refund. The guarantee lasts 14 days or until you export your 6th sudoku book, whichever comes first (a book counts once you export it as a KDP interior, a printable edition or page images). This leaves plenty of time to judge the studio while keeping the guarantee fair for everyone. Each studio has its own guarantee: books made in Word Search do not count for Sudoku.