Measure elements. Match fonts. Pick colors.

A free browser extension for Chrome, Edge & Firefox — pixel-perfect measurements, instant font detection, and one-click color picking on any site. No sign-up, no tracking, works offline.

Free forever Zero data collected Open source Works offline
Add to Chrome — Free
Edge Add-ons Firefox Add-ons GitHub Releases
01 // TOOLKIT

Powerful Design Tools

Three essential tools to enhance your web design workflow

Measurement Tool

Get precise measurements of any element on a webpage. Measure width, height, and diagonal dimensions with pixel-perfect accuracy.

Font Detector

Identify fonts used on any webpage. Discover font family, size, weight, style, and other typography details with a single click.

Color Picker

Extract colors from any element on a webpage. Get HEX, RGB, and HSL values to maintain design consistency and efficiency.

02 // OPERATION

How It Works

Simple, intuitive design tools at your fingertips

1

Install the Extension

Download and install the Web Design Ruler extension for Chrome, Firefox, or Chromium-based browsers.

Chrome extension installation screen
2

Activate the Tool

Click on the extension icon and select the tool you need, or use the right-click context menu.

Extension dropdown menu with tool options
3

Use with Precision

Interact with the webpage to measure elements, identify fonts, or pick colors with pixel-perfect accuracy.

Measurement tool in action on a webpage
03 // DEPLOY

Installation Guide

Install Web Design Ruler from official stores or as an unpacked extension

Chrome extensions page showing load unpacked process

Install from Official Stores (Best)

For Chrome: Visit the Chrome Web Store and click "Add to Chrome". For Firefox: Visit Firefox Add-ons and click "Add to Firefox".

Or Download from GitHub Releases

Download the Web Design Ruler extension files from our GitHub Releases page. Save the ZIP file to your computer and extract it.

Open Extensions Page

For Chrome: Type chrome://extensions in the address bar. For Firefox: Type about:addons in the address bar.

Enable Developer Mode (Chrome Only)

Toggle on the "Developer mode" switch in the top-right corner of the Extensions page.

Load Unpacked Extension

Click the "Load unpacked" button and navigate to the folder where you extracted the extension files. Select the folder and click "Select Folder".

Important Warning for Manual Installation

Do not delete or move the extension folder after installation. Since this is an unpacked extension, Chrome needs the folder to remain in its original location. If you delete or move the folder, the extension will stop working.

04 // SECURITY

Privacy & Security

Your privacy and security are our top priorities

No Data Collection

Web Design Ruler operates entirely on your device. We don't collect, store, or transmit any of your data or browsing history to our servers or third parties.

Limited Permissions

Our extension only requests the minimum permissions needed to function. We can only access the active tab when you explicitly activate one of our tools.

Clean Code

No ads, no trackers, no bloat — built with clean, efficient code focused solely on providing helpful design tools, by designers for designers at LXB Studio.

Open & Inspectable

The full source is public on GitHub — inspect exactly what runs in your browser, no black boxes.

Works Offline

All functionality works completely offline. No internet connection is required for the tools to operate after installation.

Why We Built This

As web designers and developers at LXB Studio, we often found ourselves switching between multiple tools to measure elements, identify fonts, and pick colors from websites. This workflow was inefficient and interrupted our creative process.

We built Web Design Ruler to solve these pain points and create a streamlined workflow for ourselves and the design community.

  • Eliminate the need for multiple extensions.
  • Create pixel-perfect designs with accurate measurements.
  • Identify and replicate beautiful typography.
  • Extract exact colors for design consistency.
  • Speed up the web design process.

We've made it free and open because we believe in giving back to the design community that has given us so much.

Web Design Ruler extension popup interface
05 // QUERY

Frequently Asked Questions

Got questions? We've got answers

Which browsers are supported?

Web Design Ruler works with Google Chrome, Firefox, and Chromium-based browsers like Microsoft Edge, Brave, Opera, and Vivaldi. Install from the Chrome Web Store, Firefox Add-ons, or download the extension files directly.

Is Web Design Ruler free to use?

Yes! Web Design Ruler is completely free to use. We created it to simplify web design workflows and give back to the design community.

Can I use the extension on any website?

Yes, you can use Web Design Ruler on any website. However, it cannot be used on browser pages like the Chrome Web Store, Settings, or New Tab page due to Chrome's security restrictions.

Why is it distributed as an unpacked extension?

We offer both options! You can install from official stores (Chrome Web Store and Firefox Add-ons) or download it as an unpacked extension for those who prefer manual installation or want to inspect the code.

Why can't I delete the extension folder?

Chrome loads unpacked extensions directly from the folder location you specify during installation. If you delete or move this folder, Chrome can no longer find the extension files, and it will stop working. This is different from extensions installed from the Chrome Web Store, which are stored in Chrome's internal storage.

How accurate are the measurements?

The measurement tool provides pixel-perfect accuracy based on the rendered elements in the browser. It measures exactly what you see on screen.

Can it identify all fonts?

The font detector can identify any font that's actively loaded and applied to text on the webpage. It cannot identify fonts in images or custom fonts that use non-standard loading methods.

How do I report bugs or request features?

We welcome your feedback! Please contact us through our contact page to report bugs or suggest new features.
SYS // LOG

Version History

Five releases · Three browsers · One mission

6
Releases
3
Browsers
14
Months Active
0
Bytes Collected
v2.2.0 2026-07-17
Latest Chrome Edge Firefox
Firefox feature parity · deep-check hardening
  • Copy All Colors on Page — one right-click harvests every rendered color, dedupes to hex, and copies them as CSS custom properties (also saved as a palette).
  • Measure tool gains an area readout and Shift-snap — hold Shift to snap to a 10 px grid; width, height, diagonal, and area all copy as CSS.
  • Full saved-fonts history — each entry shown in its own live preview, with a Web Font badge and per-item Copy CSS.
  • While eyedropping, right-click now picks the text color instead of the background.
  • First-run welcome page plus a toolbar badge (green ● while a tool is armed, ✓ when a copy lands).
  • Firefox ships with its own themed starter palette.
  • Edge: tool activation had been silently broken after the MV3 refactor (the background lost the active-tab reference) — restored.
  • Color picker samples image and video pixels through the real drawn rectangle (object-fit aware), so letterboxed or out-of-bounds hovers no longer report a false #000000.
  • The activity badge now tracks its owning tab and clears on tab close or navigation.
  • All six ported features rewritten to current conventions — single-writer storage, no innerHTML, guards throughout — and shipped byte-identical across the Chrome, Edge, and Firefox builds.
  • web-ext lint clean; CI now fails the release if the git tag and the manifest version disagree.
Manifest: MV3 × 3 Permissions: unchanged Firefox live · Chrome & Edge in review
v2.0.1 2026-05-23
Firefox
Firefox popup tool buttons fixed
  • Clicking Activate Color Picker / Font / Measure in the Firefox popup now reliably activates the tool. The response handler had been silently unreachable.
  • Clearer error notifications when a tool can't run (browser-internal pages, file:// URLs, restricted tabs).
  • popup.js rewritten as async — browser.runtime.sendMessage is awaited in a try/catch instead of passing a Chrome-style callback.
Manifest: MV3 Files changed: 1 Permissions: unchanged
v2.0.0 2026-01-13
Chrome Edge Firefox
Multi-browser rebuild · Edge native debut
  • Native Microsoft Edge support with a chrome.alarms keep-alive that defeats Edge's ~30-second service-worker termination.
  • Three purpose-built unpacked extensions — chrome/, edge/, firefox/ — each ready to Load unpacked.
  • Modern navigator.clipboard.writeText with graceful execCommand fallback for older contexts.
  • Right-click menus now reappear after a service-worker restart mid-session.
  • Slow first ping no longer mistakenly concludes the content script isn't loaded.
  • Every chrome.* callback now checks runtime.lastError instead of swallowing failures.
  • Duplicate-injection guard — repeated activations don't pile up listeners.
  • Firefox migrates to native browser.* Promise APIs throughout.
Manifest: MV3 × 3 + clipboardWrite, host_permissions + alarms (Edge) Bundle: ~125 KB
v1.1.1 2025-06-10
Firefox
Firefox debut · XSS hardening
  • First-run welcome page, animated toolbar badge (●/✓), nested right-click menu with emoji-prefixed tools.
  • "Copy All Colors on Page" quick-action — walks the DOM, dedupes, copies as CSS variables.
  • Firefox-themed default palette + theme-awareness hooks via browser.theme.onUpdated.
  • All innerHTML writes replaced with createElement + textContent for XSS hardening.
  • Background converted to browser.* Promises + async/await throughout.
  • browser.storage.sync wired up behind a syncEnabled flag for palette sync.
Manifest: MV2 + notifications, <all_urls> Firefox 78.0+
v1.1 2025-06-10
Chrome
First public release · Rebrand to Web Design Ruler
  • Renamed from LXB Studio Design Assistant → Web Design Ruler.
  • Tabbed popup UI — Color, Font, Measure, Palettes — with per-tab activation buttons and result panels.
  • Real palette management: create, rename, delete, import (.json), export. Previous build only stubbed a "coming soon" alert.
  • Recent-colors history — last 20 unique picks, persisted, rendered as a grid.
  • Default palettes expanded from one to three (LXB Studio + Material Design + Neutrals).
  • Four tool scripts collapsed into a single ~28 KB content-script.js.
  • Popup-open shortcut: Ctrl+Shift+E → Ctrl+Shift+R (the "Ruler" letter).
Manifest: MV3 Permissions: unchanged from 1.0 Chrome only
v1.0 ~2025-05-09
Internal · Never shipped
LXB Studio Design Assistant — earliest prototype
  • Three tools (color picker, font detector, measurement) in a single-pane popup.
  • One default palette (LXB Studio brand colors).
  • Palette management was a "coming soon" alert.
  • Standalone eyedropper.js used an 8× magnification screenshot-canvas approach (since absorbed).
Manifest: MV3 Chrome only Status: archived

Full source & details · github.com/LXBStudioLLC/web-design-ruler

Ready to Design with Precision?

Add Web Design Ruler to your browser and measure, match, and pick — right where you work. Free, no sign-up, no tracking.

Add to Chrome — Free