Frontend Software Engineer (Remote | Up to $90/hr) en Vitoria, España

Frontend Engineer

Position: Frontend Engineer

Type: Freelance Hourly Contract

Compensation: $90/hour

Location: Remote

About the Opportunity

This opportunity is for experienced Frontend Engineers and Full-Stack Developers interested in evaluating AI-generated web interfaces and code.

The work focuses on comparing AI-generated frontend implementations against real-world reference websites, assessing both visual fidelity and underlying code quality .

This is an evaluation-focused role rather than a traditional development position. The key requirement is the ability to identify how a webpage is constructed, recognize technical shortcuts, and provide precise, evidence-based evaluations.

What You'll Do

• Render a reference webpage and two AI-generated implementations at a 1920×1080 viewport and evaluate which version most accurately reproduces the reference.
• Compare visual fidelity across different interface states, including layout, spacing, typography, colors, borders, images, layering, and overflow behavior .
• Review the source code of AI-generated implementations and assess HTML structure, CSS architecture, responsiveness, maintainability, and implementation quality .
• Identify technical shortcuts such as excessive hardcoded positioning, unnecessary absolute positioning, poorly structured markup, or image-based recreations.
• Test responsive behavior across different viewport sizes and identify layout or usability defects.
• Use browser DevTools to inspect elements, computed styles, DOM structure, and interactive states.
• Provide specific, evidence-based written justifications explaining why one implementation is stronger than another.
• Identify genuinely broken evaluation tasks while distinguishing them from tasks that are simply challenging.

Required Qualifications

• 3–8 years of professional web development experience , primarily in frontend or full-stack engineering.
• Strong hands-on experience with HTML, CSS, JavaScript, responsive web development, and modern frontend engineering practices .
• Deep understanding of semantic HTML, Flexbox, CSS Grid, media queries, and responsive layouts .
• Ability to read and understand both modern and legacy web layouts , including float-based and table-based designs.
• Strong proficiency with browser Developer Tools , including DOM inspection, computed styles, viewport testing, and interactive state debugging.
• Comfortable working from the command line, including extracting archives, running local development servers, and troubleshooting asset paths .
• Sufficient JavaScript knowledge to understand how scripts interact with the DOM and user interactions.
• Strong professional written English and the ability to provide clear, detailed technical justifications .
• Strong attention to detail and the ability to identify subtle visual and structural differences.

Preferred Qualifications

• Prior experience with RLHF, preference labeling, AI model evaluation, structured code review, or human-feedback projects .
• Pixel-perfect design-to-code experience, including work with design systems, templates, or production web interfaces .
• Knowledge of web accessibility , including ARIA, semantic landmarks, and heading hierarchy.
• Familiarity with common failure patterns in AI-generated frontend code .
• Experience with web scraping, website archiving, DOM parsing, or working with complex crawled website structures .
• Previous experience completing AI evaluation projects and working in multi-hour evaluation sessions.

Equipment Requirements

• Desktop or laptop capable of displaying a 1920×1080 viewport .
• Ability to run a local development environment and static web server .
• Administrator access to your own computer for installing required development tools.

Important Project Requirements

• Each evaluation unit typically takes 2–3 hours and is completed within a defined time window.
• This is not microtask work and requires the ability to dedicate uninterrupted blocks of time to individual evaluations.
• A functioning local development environment is required.
• The role is intended for practicing web developers with strong frontend and UI implementation expertise.
• Backend-only, ML/data-science-only, mobile-native-only, and DevOps-only backgrounds are generally not suitable for this evaluation work.

Compensation

• Competitive compensation of $90/hour.
• Independent contractor engagement.
• Compensation is based on completed evaluation work in accordance with project requirements.

Application Process

1. Easy Apply on LinkedIn
2. Check Email for Next Steps
3. Participate in Resume Evaluation & Interview Stage