A full stack developer works on both the user-facing and back-end elements of websites and applications. A junior full stack developer works under the supervision of a senior developer. In this position, your duties include handling coding responsibilities for front-end, user-facing elements. You use JavaScript, HTML, and CSS for this part of the job. You also use languages such as Python, SQL, and PHP for the back-end system of a website, including the database, cloud network, and security features. In addition to coding, you test and debug your developments and work with other team members using development strategies and methodologies.