I wanted there to be an easy way to complete crosswords together that didn’t need people to pass a phone back and forth or for a copy of the crossword to be made in a shared Google Spreadsheet.
Several People are Solving is a lovely React app which started as a fork of The Guardian’s Frontend repo in order to further develop their crossword component.
See author Chris Zetter’s article on how he then introduced WebSockets (within a Rails application) to facilitate real-time collaboration.
The crosswords are updated regularly so what are you waiting for? Get solving!