Frontend Code Evaluator - Expert

mercor; Österreich; Remote; EUR 95,000 - 128,000; Full time

Job summary

Mercor is seeking a Frontend Engineer to evaluate web replications for AI research labs. This contract role focuses on pixel‑perfect rendering, layout fidelity, and detailed rationale for judgments.

You will work remotely, contribute to UI markup, and document decisions with precise language, using HTML/CSS, JavaScript basics, and browser devtools in a fast-paced setting.

Qualifications

• 3+ years of professional web development experience.
• Fluency in hand-written HTML and CSS.
• Working command of browser devtools.
• Enough JavaScript to read scripts and understand DOM manipulation.
• Comfort in a terminal for local server setup.
• Strong written English and discipline to justify judgments.

Responsibilities

• Render a reference page and two candidate replications side by side at desktop width.
• Diff layout fidelity in detail, including box model, typography, color, image handling, and overflow.
• Inspect underlying markup with browser devtools to distinguish genuinely correct replications from those that merely look correct.
• Evaluate responsive behavior and semantic quality, ensuring proper use of flexbox and grid.
• Write structured rationales for every judgment, ranking defects by importance in precise language.
• Flag ties, ambiguous cases, and broken task items rather than forcing a preference.

Skills

HTML/CSS

Browser devtools

JavaScript basics

Terminal / local server

English writing

Job description

About the job

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 Engineer — Web Replication Preference Rater
Type: Contract
Compensation: $90/hour
Location: Remote

Role Responsibilities

• Render a reference page and two candidate replications side by side at desktop width. Judge which is the closer reproduction.
• Diff layout fidelity in detail, including box model, typography, color, image handling, and overflow.
• Inspect underlying markup with browser devtools to distinguish genuinely correct replications from those that merely look correct.
• Evaluate responsive behavior and semantic quality, ensuring proper use of flexbox and grid.
• Write structured rationales for every judgment, ranking defects by importance in precise language.
• Flag ties, ambiguous cases, and broken task items rather than forcing a preference.

Qualifications Must-Have

• 3+ years of professional web development experience, primarily in frontend or full-stack work.
• Fluency in hand‑written HTML and CSS.
• Working command of browser devtools.
• Enough JavaScript to read scripts and understand DOM manipulation.
• Comfort in a terminal for local server setup.
• Strong written English and discipline to justify judgments.

Preferred

• Prior RLHF, preference labeling, or model evaluation work.
• Code review or technical assessment background.
• Pixel‑perfect design‑to‑code experience.
• Web accessibility expertise (WCAG, ARIA).
• Familiarity with LLMs' typical failures in codegen.
• Web scraping or DOM parsing experience.