sudoku.tn1ck.com
sudoku.tn1ck.com is full featured sudoku app with a decently polished web UI. It has support for notes, hints, keyboard shortcuts, a timer that stops when the window loses focus, 100 sudokus for each of the difficulties and first class citizen support for desktop (mobile or mouse) and mobile. I started this project out of frustration for the available web options back then (2017), this has since then greatly improved. The project is open source on Github.