DevDocs is an Electron-based application which enables offline documentation browsing for many web and other development technologies.
All the available documentations are listed in a left-hand sidebar. Click 'Select documentation' bottom-left, check the boxes next to anything you need, click Save and the new technologies are collected together at the top of the sidebar.
ver: 0.6.4 / Jun 26.2017
ver: 0.1.0 / May 02.2017