KA User Search
Khan Academy doesn't have any practical way of searching for users, something which I find myself wanting to do often.
This website concatenates data from several scrapes of KA programs and users (some done by me, some by others).
The result is a list of KA users/nicknames which filters as you type. (If a user changed their nickname, they will be listed by all nicknames to ensure they are findable.)
This project was an experiment in infrastructure minimalism.
The backend is a single NodeJS file, with a dependency only to connect to the database.
The frontend is a single HTML file, which is of course available.
Since there is so little code here, it is closed-source, though I do track it with git.