I was curious if it is possible to submit a run using the API. Using your API key, and using some external software, I was wondering if it would be possible. The only reason I want to know is to submit a run to https://speedrun.com/the_site

even if you could im not sure if it would submit it as the_site doesnt have categories

It is possible to submit runs through the API. In fact, Livesplit has the option to submit a run in the splits editor of a game, under "Additional info" (I never used it myself):

But as @SioN said, it won't help you for this "game" because there are no categories.

It is possible to submit runs with the api but it's not possible to submit to any of the forums because they dont have any categories or levels (I think)

someone should submit a run to "staff test"

We’ve got to figure out the categories

Any%

Dear Elo, please create categories for the forum games. Thanks.