We recommend using an IDE which supports the PHP language and Twig syntax. For this purpose, we suggest using one of the following IDEs.
PhpStorm is a comprehensive IDE which supports all PHP language features. PhpStorm also includes a wide range of leading edge front-end technologies, such as CSS, Sass, Javascript, as well as Twig syntax highlighting.
Atom is a customisable editor working across operating systems. It can be extended to also support Twig syntax.
*) All required Atom packages can be found using the embedded package control pane of the Atom IDE. This pane can be found in Atom: Settings > Install.
As an alternative to the PhpStorm and Atom IDEs, we also recommend Sublime Text with the respective plugins for syntax highlighting.