What is a Full Stack Developer? The full stack developer definition is “someone who can work on both the back-end and front-end of systems.” This means that they can develop fully fledged platforms (with databases, servers and clients) which don’t need other applications to function. What does a Full Stack Developer do? The Full Stack Engineer job description includes using a range of different technologies and languages (such as Java, JavaScript, HTML, PHP, C#) to develop applications. Full Stack Developers approach software holistically since they cater to both user experience and functionality. Full Stack Developer duties include: Participating in the design and creation of scalable software Writing clean, functional code on the front- and back-end Testing and fixing bugs or other coding issues