Web Development Expert - Fully Remote | Upto $90/hr

Mercor connects elite creative and technical talent with leading AI research labs. Headquartered in San Francisco, our investors include Benchmark , General Catalyst , Peter Thiel , Adam D'Angelo , Larry Summers , and Jack Dorsey .

Position: Frontend EngineerType: ContractCompensation: $90/hourLocation: Remote

Role Responsibilities

Render a reference page and two candidate replications at 1920×1080. Judge which is the closer reproduction, state by state.

Diff visual fidelity in detail: box model and spacing, typography (family, size, weight, line-height, letter-spacing), color and border treatment, image and asset handling, z-order, and overflow.

Read the source of both attempts and grade construction quality. Distinguish a replication that is genuinely correct from one that merely looks correct at one viewport.

Test responsiveness. Identify defects such as a nav bar that looks right at 1920px but collapses at 1400px.

Write specific, evidence-cited justifications for every preference. Provide detailed explanations like "B nests the article body in a single absolutely-positioned div, so the text overlaps the footer below 1600px, while A uses normal document flow."





Use the "this task is broken" escape hatch with judgment. Distinguish a task that genuinely cannot be completed from one that is merely hard.

Qualifications

Must-Have

3–8 years of professional web development experience in frontend or full-stack work.

Fluency across web eras, including legacy layouts like used for layout.

Command of hand‐written HTML and CSS : semantic markup, flexbox, grid, media queries, and legacy float- and table-based layouts.

Browser DevTools as muscle memory.

Command-line comfort: unzipping an archive, standing up a static local server, and untangling a broken image reference.

Enough JavaScript to read a page's scripts and understand their DOM impact.

Professional written English for task justification.

Preferred

Prior RLHF , preference-labeling, model-evaluation, or structured code-review work.

Pixel-perfect design-to-code experience.

Accessibility expertise (ARIA , semantic landmarks, heading hierarchy).

Familiarity with how LLMs fail at code generation.

Web scraping, archiving, or DOM-parsing background.

More than one completed Mercor project and availability in contiguous multi-hour blocks.

📌 Software Engineer Php/React — Remote & Flexible Perks (Madrid)
🏢 Idealista
📍 Madrid