As the title says, I think expanding Codeforces API would be a good idea.

For example, adding a simple submit API call would ease the development of CLI tools and IDEs. An API call to list problem submissions, and one to download submission code would allow course organizers, like myself, to check for plagiarism. Every functionality which is available via "website", should be somehow accessible through the API. I know it`s a lot of work, but having such thing would be terrific.

Also, having a public API would encourage other judges to also expose theirs, and maybe set an unifying standard for online judges.

I am aware that there are some alternatives, like https://github.com/online-judge-tools/oj, but they don`t have full functionality, and can break when CF decides to change anything.

Let me know what you think, or whether this is already planned.