About the work We're building a high-quality dataset of human preference judgments on AI-generated frontend code. Each task hands you a reference web page — crawled from the real internet, delivered as a full zipped site tree plus screenshots of its default view and, on some pages, additional states reached by hovering, clicking, or scrolling. Alongside it come two model attempts, A and B, each a zipped self-contained site tree.

You download all three, run them locally, view each at a 1920×1080 viewport, interact with them to reach every required state, then open the source of both attempts and grade them against each other — on visual fidelity per state, and on how the code is actually constructed. Structure and responsiveness are explicitly part of the rubric, not just the render. The defining skill is not that you can build a page — it's that you can open someone else's page and tell how it was built and where it cheats.

Please read before applying Each unit takes roughly 2–3 hours and is timed. if you can only offer scattered 15-minute windows, you will not be able to finish a unit. You need a real local development environment. A tablet, a Chromebook, or a locked-down work machine that cannot run a local static server will not work for this project.

We are not onboarding net-new experts to this project. Render a reference page and two candidate replications at 1920×1080 and 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 — distinguishing a replication that is genuinely correct from one that merely looks correct at one viewport. Hardcoded pixel offsets, absolute positioning standing in for real layout, inline style soup, a single undifferentiated div tree, or a screenshot pasted in as an instead of a rebuilt section.

Test responsiveness: a nav bar that looks right at 1920px but collapses at 1400px is a defect, and you should be able to say precisely why. Use the "this task is broken" escape hatch with judgment: distinguish a task that genuinely cannot be completed from the screenshots provided from one that is merely hard. You're a fit if you have 3–8 years of professional web development experience, shipping web interfaces for a living, primarily in frontend or full-stack work.

The reference pages are real crawled sites — one is a small charter-fishing business built in the table-and-image-map tradition, another a corporate press-release page with stacked navigation rows and social share widgets. If your entire career happened inside a modern component framework and you have never authored raw CSS or seen a table used for layout, you will misjudge many of these pages. Command of hand-written HTML and CSS: semantic markup, flexbox, grid, media queries, and legacy float- and table-based layouts you can read and reason about.

You should be able to look at a rendered layout and predict what's holding it together before opening Dev Tools.





Browser Dev

Tools as muscle memory — setting an exact viewport, walking the element tree, checking computed styles, watching what a hover handler mutates. Command-line comfort: unzipping an archive, standing up a static local server because the relative asset paths demand it, and untangling a broken image reference rather than giving up and grading from the screenshot.

Enough Java

Script to read a page's scripts and understand what they do to the DOM, even if you don't write JS daily. Professional written English. Equipment A desktop or laptop that displays a 1920×1080 viewport.

Administrator rights on your own machine, so you can install and run a local server. Prior RLHF, preference-labeling, model-evaluation, or structured code-review work — the strongest single signal. Pixel-perfect design-to-code experience: agency work, design systems, template production.

Accessibility expertise (ARIA, semantic landmarks, heading hierarchy) — you'll notice immediately when an attempt renders a heading as a styled.. Familiarity with how LLMs fail at code generation. Web scraping, archiving, or DOM-parsing background — comfort with messy crawled site trees.

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

Note: this seat is for practicing web developers. Backend-only, ML/data-science-only, mobile-native-only, and Dev Ops-only engineers do not have the UI instincts this requires, however strong they are otherwise. Designers who do not code cannot grade the source axes at all. Framework-only engineers who have never authored CSS outside a component library will struggle with the legacy reference pages.

📌 Frontend code evaluation specialist (Milano)
🏢 Mercor
📍 Milano