Amuse Labs is the leading provider of web-based software for crossword puzzles and other knowledge games, such as sudoku and word search. Its platform powers puzzles for publishers like The Washington Post (link), the Los Angeles Times (link) the New Yorker (link), and The Atlantic (link). The platform is fully responsive and supports more than a dozen languages. It supports multimedia and can be white labelled and customized for a particular brand or publication to provide a native look and feel. See examples of use cases at https://amuselabs.com/gallery.