Who doesn't like free stuff? Especially when it comes to knowledge-boosting and possibly career-improving free stuff. Udemy has a boatload of free online courses for beginner, intermediate, and advanced learners.
Among the free courses are Java tutorials, MySQL tutorials, and iOS apps creation tutorials, but there are also free courses on all sorts of topics, including hobbies (electric guitar playing) and productivity and entrepreneurship ("everyday mind mastery").
It's not very easy to see or filter all the free courses at once, but scrolling through the search results should be well worth the effort.
After all, this being the new year, it's a great time to start or futher your learning, whatever your interests. Enjoy!