CMU Course Catelog API
This API is a bit different than the URL based APIs we saw from Google because CMU's API is actually a python library that you have to download. However, what it does is pull the course catelog web pages and scrape them for the data, returning them to you in a nice form.
You can get classes scheduled for semesters, get descriptions of the course, and many more things.
You will have to download the API from here
Look at an example here