edX courses

There are a lot of free courses on edX on almost every topic. You can pay for certificates but auditing the material is usually free.

I am currently working though the Data Science courses from HarvardX. So far I have found them useful. The textbook is great and the videos are a nice addition. There are exercises you can do on Datacamp but most Datacamp exercises can be found in the textbook as well. I prefer doing the exercises in RStudio in advance and copying them into Datacamp to check if I have made a mistake.

You can find the courses here.