Develop new user-facing features Build reusable code and libraries for future use Ensure the technical feasibility of UI/UX designs Optimize application for maximum speed and scalability Assure that all user input is validated before submitting to back-end Collaborate with other team members and stakeholders Proficient understanding of web markup, including HTML5 and CSS3 Basic understanding of server-side CSS pre-processing platforms, such as LESS and SASS Strong knowledge of web standards Proficient understanding of cross-browser compatibility issues and ways to work around them Familiarity with differences in other HTML5 based views, such as ones in email clients Knack of adhering to best design practices Fair understanding of JavaScript programming and DOM manipulation Good understanding of SEO principles and ensuring that the application will adhere to them