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) (Madrid)
🏢 Synthires
📍 Madrid