Yes, you can get very nice web development skills online for free. There are so many options out there such as Lynda, Khan Academy, Coursera, Udemy among others that allow you to learn web development online. Here I`m going to highlight my favorite platform and tell you why it is so.
In the year 2014, I sought out to learn programming. Through YouTube and blogs, I had learned that Python was a good programming language to start with. I googled programming learning sites and code academy stood out from the others. Why you ask, because code academy has the best interface. As seen below there are three parts in the interface: instructions,editor and live preview.
This section displays a set of instructions that you are to initiate into the editor. But before the instructions is an example or two of what the code is supposed to look like.
Live Preview:(Yellow area)
Here, the result of your code is shown once you hit the run button below the editor.
Below is an image showing the bunch of web development courses that you can take and the estimated number of hours it can take you for each.
However, if you want full access to all courses, I advice that you pay for their PRO account which will allow you to undertake projects such as creating a complete website as a way of determining your level of understanding.