HTML​/CSS - Senior Developers - AI Training - Seattle

HTML/CSS - Senior Developers - AI Training - USA

Prolific is not just another player in the AI space – we are building the biggest pool of quality human data in the world.

We're looking for Senior HTML/CSS Developers to join our Expert Network to help train and evaluate cutting‑edge AI models. If you have a background in Software Engineering or Frontend Development, we'll send you a quick 10‑ to 15‑minute test to assess your skills. If successful, you'll be invited to join Prolific as a participant, where you'll get paid to help AI understand and produce high‑quality frontend code and design implementation.

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

• Educational Background: a BSc or higher in Computer Science, Software Engineering, Web Development, or a closely related technical field.
• Professional
  
  Experience:
  
  real‑world experience as a Senior Frontend Developer or UI Engineer specialising in HTML/CSS.
• Coding Proficiency: ability to independently build complex, responsive layouts and components without relying on frameworks or libraries.
• Deep Domain Knowledge: expert understanding of the CSS cascade, specificity, the box model, Flexbox, CSS Grid, accessibility standards (WCAG), and cross‑browser compatibility.
• Code Quality: a high standard for clean, semantic markup and maintainable CSS, including adherence to BEM methodology, design tokens, and modern CSS standards.

• Evaluate Code Accuracy: review AI‑generated HTML/CSS for functional correctness, semantic structure, and adherence to best practices.
• Validate Logic & Reasoning: audit the step‑by‑step explanations provided by AI for layout solutions and styling approaches to ensure they are technically sound.
• Conduct Execution Testing: render model‑generated markup and style sheets in appropriate environments to verify visual output and cross‑browser behaviour.
• Annotate Model Performance: identify areas where a model produces inaccessible markup, inefficient selectors, deprecated attributes, or hallucinated CSS properties.
• Refine Technical Logic: provide structured feedback on how models reason through responsive design, component architecture, or design system implementation.

• Core
  
  Languages:
  
  expert mastery of HTML5 and CSS3/4, including custom properties, animations, and modern layout systems.
• Frameworks & Methodologies: extensive experience with Tailwind CSS, SASS/SCSS, or CSS Modules, and familiarity with component‑driven design systems.
• Testing & Tools: proficiency with browser Dev Tools, accessibility auditing tools (axe, Lighthouse), and cross‑browser testing platforms.

You can start in just 15 minutes, earning competitive pay rates up to $40/hr
, with flexible hours and the ability to work from home.

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 Prolific may process, where Prolific may process your personal information, its purposes for processing your personal information, and the rights you can exercise over Prolific use of your personal personal information.