You can install this extension on Brackets if you plan to use Sightly as the markup. The extension provides you with features such as syntax highlighting and code completion.
Brackets extension provides front-end developers an AEM templating tool with which they are familiar. The idea is to bring more front-end developers to AEM template designing. Use CRXDE Lite to create a basic structure of your project. Then create a package and download the package. Unzip the package and open it in Brackets. Make the changes; Brackets extension allows you to automatically sync with the Oak repository.
For more information, see Adobe’s documentation.