A CSS animations developer uses CSS (Cascading Style Sheets) to create and manage animations on web pages. They create dynamic user interface components, such as buttons, dropdowns or sliders, that respond to user interactions. Their work includes creating keyframes that define the animation sequence, setting animation timing, and controlling animation speed, direction, and delays. They also ensure that animations run smoothly across different browsers and devices. They work closely with UX/UI designers and other web developers to enhance the overall user experience and improve the aesthetics of the website.