Share a puzzle with a link
Same grid for everyone. There is a share button at the top so you can pass the exact puzzle around, whether you started it on the site or in the app.
I used to send a screenshot and say try this one. Half the time they got a different puzzle, or a different difficulty. Sometimes they tried to copy the grid from a blurry photo. I wanted a link that opens the same puzzle.
The share control sits at the top of the play screen. Tap it, copy the link, send it. Whoever opens it gets your starting grid, not a random one that feels close.
Where you created the puzzle does not matter. Generate it on the website and the link works. Generate it in Coffee Sudoku on your phone and the link still works. Same layout, same difficulty.
I tried it the way I actually play: finish something nasty, paste the link into a chat, and watch someone else wrestle the same grid. I also opened a link from the browser on my phone and back. The clues matched every time.
In a group chat it means you are all staring at the same empty cells. No arguing about which screenshot was the right one.
Start a puzzle anywhere Coffee Sudoku runs, tap share at the top, and pass the link. Short and useful.