4 items
Pixel-perfect Image Mockup Diff, Box Model Measure, Eyedropper & Token Matcher, WCAG Contrast Checker & Grid Inspector. Pixel-perfect design QA, right on the page. DevLens Design QA helps developers and designers compare what was built with what was designed: overlay the mockup, measure the spacing, check the colours and test the breakpoints. MOCKUP OVERLAY • Drop or paste a PNG, JPG or WebP exported from your design tool • Set opacity, use normal or difference blend, and nudge the position 1 px or 10 px at a time • 1x or 2x render scale for retina exports • Overlay position is remembered per page MEASURE • Hover any element to see its box model: content, padding, border and margin in pixels • Computed font family, size, weight, line height and colour COLOUR AND CONTRAST • Eyedropper to pick any colour on screen, shown as HEX, RGB and HSL • Match picked colours to your own design tokens (paste name → hex pairs) • WCAG contrast checker with AA and AAA results for normal and large text GRIDS AND VIEWPORTS • Column grid overlay (columns, gutter, margin) and an 8 px baseline grid • One-click viewport widths: 320, 375, 768, 1024, 1280 and 1440 px, or a custom width PRIVATE BY DESIGN • In-page tools live in an isolated Shadow DOM, so page styles never leak in or out • Site access is optional and granted per site • Your mockups never leave your device. No accounts, no analytics, no network requests Part of DevLens, a set of focused, offline developer tools for Chrome.
Nov 4, 2026
rating_count is the Chrome Web Store ratings count, not a written-review count.
Media assets
Screenshots and videos on the listing.
Has promo video
Whether the listing includes at least one video.
Languages
Declared language locales.
Developer website
Listing exposes a developer website URL.
Contact email
Listing exposes a contact email.
Keyword in name
Case-insensitive substring match in the name.
Keyword in description
Case-insensitive substring match in the description.
Keyword occurrences in description
Count of case-insensitive occurrences in the description.
Category user-count percentile
Share of same-category extensions with fewer users (null if unknown).
These are transparent listing completeness / keyword signals, not a prediction of Chrome Web Store search ranking.