A Web Application Developer II is a mid-level software professional who designs, develops, tests, and maintains web-based applications. They work closely with other developers, designers, and stakeholders to implement new features, optimize performance, and fix bugs. This role typically requires a solid understanding of programming languages like JavaScript, HTML, and CSS, along with backend technologies such as Node.js, PHP, or Python. Web Application Developer IIs are also expected to follow best coding practices and may mentor junior developers.