HTML/CSS - Senior Developers - AI Training - USA

About Prolific

Prolific is building a large pool of quality human data used by AI developers, researchers, and organizations.

The role

We're looking for Senior HTML/CSS Developers to join an Expert Network to help train and evaluate cutting-edge AI models. Candidates with a background in Software Engineering or Frontend Development will complete a short skills assessment. Successful applicants will join as paid participants helping AI understand and produce high-quality frontend code and design implementation.

Researchers looking for these skills tend to pay up to $40/hr, depending on skills and experience. Participants must be prepared to complete paid tasks that require one hour of uninterrupted work, though many tasks are shorter.

What you'll bring

• BSc or higher in Computer Science, Software Engineering, Web Development, or a closely related technical field
• Real-world experience as a Senior Frontend Developer or UI Engineer specialising in HTML/CSS
• Ability to independently build complex, responsive layouts and components without relying on frameworks or libraries
• Expert understanding of the CSS cascade, specificity, the box model, Flexbox, CSS Grid, accessibility standards (WCAG), and cross-browser compatibility
• High standards for clean, semantic markup and maintainable CSS, including adherence to BEM methodology, design tokens, and modern CSS standards

What you'll be doing in the role

• Review AI-generated HTML/CSS for functional correctness, semantic structure, and adherence to best practices
• Audit AI explanations for layout solutions and styling approaches to ensure technical accuracy
• Render generated markup and stylesheets to verify visual output and cross-browser behaviour
• Identify inaccessible markup, inefficient selectors, deprecated attributes, or hallucinated CSS properties
• Provide structured feedback on responsive design, component architecture, and design system implementation

Key Technologies

• Expert mastery of HTML5 and CSS3/4, including custom properties, animations, and modern layout systems
• Experience with Tailwind CSS, SASS/SCSS, or CSS Modules, and familiarity with component-driven design systems
• Proficiency with browser DevTools, accessibility auditing tools such as axe and Lighthouse, and cross-browser testing platforms

By submitting your application, you agree that Prolific may collect your personal data for recruiting and global organisation planning. Prolific's Candidate Privacy Notice explains what personal information may be processed, where it may be processed, its purposes, and the rights you can exercise regarding your personal information.