Firefox Browser Add-ons
  • Extensions
  • Themes
    • for Firefox
    • Dictionaries & Language Packs
    • Other Browser Sites
    • Add-ons for Android
Log in
Preview of Youtube Watch Thumbnails

Youtube Watch Thumbnails by mosunset

Display YouTube video thumbnails directly on the watch page. This extension automatically shows thumbnail images next to the channel icon, allows you to view all available thumbnail sizes, and provides a hover zoom feature. Click the thumbnail to

0 (0 reviews)0 (0 reviews)
No UsersNo Users
Download Firefox and get the extension
Download file

Extension Metadata

Screenshots
About this extension
YouTube Watch Thumbnails

A browser extension that displays YouTube video thumbnail images directly on the watch page, making it easy to view and check all available thumbnail sizes.

Features
  • Automatic Thumbnail Display: Automatically displays thumbnail images next to the channel icon on YouTube watch pages
  • Hover Zoom: Hover over the thumbnail to see an enlarged preview (1.75x scale)
  • Thumbnail View Page: Click the thumbnail to open a dedicated page showing all available thumbnail resolutions (WebP and JPG formats)
  • Multiple Resolutions: View thumbnails in various sizes including maxresdefault, hq720, sddefault, and more
  • Image Size Information: See the actual dimensions (width × height) of each thumbnail image

How It Works

When you visit a YouTube video page, the extension automatically:
1. Detects the video ID from the URL
2. Displays the thumbnail image next to the channel icon
3. Allows you to hover to zoom or click to view all sizes

The extension works on:
- Regular watch pages (/watch?v=)
- YouTube Shorts pages (/shorts/)
- All YouTube subdomains (www.youtube.com, m.youtube.com, etc.)

Privacy

This extension does not collect, store, or transmit any user data. All operations are performed locally in your browser. The extension only accesses YouTube pages to display thumbnail images.

Technical Details
  • Built with React and TypeScript
  • Uses WXT framework for cross-browser compatibility
  • No external API calls or data collection
  • Open source and transparent
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:

  • Access browser tabs
  • Access your data for sites in the youtube.com domain
  • Access your data for m.youtube.com
  • Access your data for www.youtube.com
  • Access your data for youtube.com

Data collection:

  • The developer says this extension doesn't require data collection.
Learn more
More information
Add-on Links
  • Support site
  • Support Email
Version
4.0.0
Size
183.11 KB
Last updated
5 days ago (Nov 6, 2025)
Related Categories
  • Web Development
  • Photos, Music & Videos
  • Games & Entertainment
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.