Firefox Browser Add-ons
  • Extensions
  • Themes
    • for Firefox
    • Dictionaries & Language Packs
    • Other Browser Sites
    • Add-ons for Android
Log in
Preview of Designer Dev Mode

Designer Dev Mode by spphhc

Designer Dev Mode is a Chrome extension for visually inspecting websites. It shows layout structure, spacing, design tokens, assets, accessibility hints, and CSS values directly in a Dev Mode style panel.

0 (0 reviews)0 (0 reviews)
Download Firefox and get the extension
Download file

Extension Metadata

About this extension
Designer Dev Mode is a Chrome extension that brings a Figma Dev Mode inspired inspection workspace directly into the browser. It helps designers, developers, and product teams analyze live websites visually, inspect layout structure, review spacing, extract design tokens, find assets, and understand the CSS behind selected elements.

After opening the extension on a webpage, Designer Dev Mode scans the visible page and builds a structured layer tree of detected elements. You can select elements from the layer list or directly from the page, then inspect their size, margin, padding, gap, typography, colors, borders, radius, shadows, computed CSS, and HTML attributes. Visual overlays make it easier to understand spacing and element boundaries directly on the website.

The extension also detects design tokens from CSS variables and inferred page styles, including colors, typography, spacing, border radius, and shadows. Tokens can be reviewed, edited, and exported as JSON. Selected elements can be adjusted live through the inspector, including font family, font size, weight, line height, letter spacing, text color, background color, border styling, opacity, dimensions, layout, spacing, and corner radius.

Designer Dev Mode includes asset detection for images, icons, inline SVGs, media sources, and background images, with download support for collected assets. It also provides accessibility checks with helpful hints, an integrated console view for page logs and JavaScript execution, per-site autosaving for design changes, and a reset option to restore edited styles.
Rated 0 by 0 reviewers
Log in to rate this extension
There are no ratings yet

Star rating saved

5
0
4
0
3
0
2
0
1
0
No reviews yet
Permissions and data

Required permissions:

  • Download files and read and modify the browser’s download history
  • Access browser tabs

Optional permissions:

  • Access your data for all websites

Data collection:

  • The developer says this extension doesn't require data collection.
Learn more
More information
Add-on Links
  • Copy add-on ID
Version
0.2.9
Size
1,015.71 KB
Last updated
3 days ago (May 15, 2026)
Related Categories
  • Web Development
License
MIT License
Version History
  • See all versions
Add to collection
Report this add-on
Go to Mozilla's homepage

Add-ons

  • About
  • Firefox Add-ons Blog
  • Extension Workshop
  • Developer Hub
  • Developer Policies
  • Community Blog
  • Forum
  • Report a bug
  • Review Guide

Browsers

  • Desktop
  • Mobile
  • Enterprise

Products

  • Browsers
  • VPN
  • Relay
  • Monitor
  • Pocket
  • Bluesky (@firefox.com)
  • Instagram (Firefox)
  • YouTube (firefoxchannel)
  • Privacy
  • Cookies
  • Legal

Except where otherwise noted, content on this site is licensed under the Creative Commons Attribution Share-Alike License v3.0 or any later version.