A JetBrains WebStorm developer uses the WebStorm integrated development environment (IDE) to create, test, debug, and manage web applications. They predominantly use JavaScript and related technologies like HTML, CSS, Node.js, React, Angular, and Vue.js. They utilize WebStorm's intelligent coding assistance, including auto-completion, error detection, and refactoring capabilities. They also use built-in debugging and testing tools for client-side and server-side JavaScript. Additionally, they leverage WebStorm's version control system integration for effective collaboration and seamless updates. They are responsible for ensuring high-quality, efficient, and maintainable code, contributing to the development of robust web solutions.