WordPress has a distraction-free feature, the best way I put this feature to use is by doing the following:
Press F11 within chrome to go full screen, enable DF mode within WordPress <shift> <alt> <w>, and use the shortcut command <ctrl> <shift> <f>.
This enables a full-screen mode that can be considered completely distraction free.
In addition to this, there are a number of offline tools that also help if the goal is to keep things offline or would like to work in a more secure way.
The ones I enjoy most (so far) are:
All of these are useful in their own way and have their own set of features.
I will add more to this article as I see fit, but these are the highlights for the moment. This WordPress article also has a ton of information on this subject: