HTML/CSS – Senior Developers – AI Training – UK

Company: Prolific
Apply for the HTML/CSS – Senior Developers – AI Training – UK
Location: London
Job Description:

About Prolific

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

Over 35,000 AI developers, researchers, and organizations use Prolific to gather data from paid study participants with a wide variety of experiences, knowledge, and skills.

The role

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 looking for your skills tend to 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.

What you’ll bring

  • 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.

What you’ll be doing in the role

  • 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 stylesheets 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.

Key Technologies

  • 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 DevTools, accessibility auditing tools (e.g., axe, Lighthouse), and cross‑browser testing platforms.

#J-18808-Ljbffr…

Posted: April 28th, 2026