Brackets
Brackets is an open-source code editor that has been specifically designed for working in HTML, CSS and JavaScript, and subsequently has been built in HTML, CSS and JavaScript.
Brackets comes with a crisp user interface in the form of Quick Edit. This is where you can put context-specific code and edit with inline tools, instead of cluttering up your coding environment with various panels and icons.
Brackets also has a really useful feature called Live Preview, which works directly with your browser in order to push code edits instantly. You can jump back and forth between your source code and the browser view to see your changes.
Brackets is a solid editor and has everything you need for working with files and directories, and creating new files. The code completion features let you quickly assemble apps without knowing the exact syntax. If you need assistance code syntax and code options, then the Quick Edit option provides help along the way.
Brackets also offers a strong extension framework. There are numerous extensions available, which can be browsed and installed via the Extension Manager, located in the File menu or by clicking the icon in the upper right corner of the main interface.
Overall, Brackets is a pleasure to code with. The interface is easy to navigate, and the extensions offer a variety of options. The Live Preview option is a really helpful tool, because you get instant feedback on any changes to your code.
According to Adobe, best of all, because Brackets is open source, and built with HTML, CSS and JavaScript, by using it, you can help to build the best code editor for the web (if you want).