Frontend Engineer
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Frontend Engineer

Type: Freelance Hourly Contract

Location: Remote

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. Render a reference webpage and two AI-generated implementations at a 1920×1080 viewport and evaluate which version most accurately reproduces the reference.
Review the source code of AI-generated implementations and assess HTML structure, CSS architecture, responsiveness, maintainability, and implementation quality .
Test responsive behavior across different viewport sizes and identify layout or usability defects.
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 .
~ 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.
Ability to run a local development environment and static web server .
Important Project Requirements
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.
Independent contractor engagement.
Compensation is based on completed evaluation work in accordance with project requirements. Participate in Resume Evaluation & Interview Stage

Hay opciones de teletrabajo/trabajo desde casa disponibles para este puesto. xqbhyrx

Hay opciones de teletrabajo/trabajo desde casa disponibles para este puesto.

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