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

- Easy Apply on LinkedIn
- Check Email for Next Steps
- Participate in Resume Evaluation & Interview Stage

📌 Frontend Engineer (Remote | Up to $90/hr) (Huelva)
🏢 Synthires
📍 Huelva