A range of tools are available to make your life as a Moodle developer easier, and your development faster. These range from editor and IDE integrations, to linting tools which helps your code meet Moodle's Coding style, to build tools essential to the build process.
These tools are discussed and summarised here.
Moodle's primary development language is PHP, and all code should pass basic PHP linting checks as a minimum, however all new PHP code must also meet the Moodle Coding style rules. To make this task easier tools such as the PHPCodeSniffer are available.
See the NodeJS and Grunt for more information on these build tools.
Along with language-specific tools, several tools have been created to make your day-to-date life as a developer easier. Perhaps the most widely used of these amongst those regularly contributing to the core Moodle project is the Moodle Development Kit, or MDK as it is typically known.