Thumbnail Grabber for YouTube by ThumbnailsGrabber

Grab the thumbnail of any YouTube video or Short in one click, straight from the video page.

Open a video, click the icon, and the popup lists every thumbnail size YouTube stores for it: max resolution (1280x720), standard (640x480), high quality (480x360), medium (320x180), and the oar2 image (the vertical 9:16 thumbnail on Shorts; some regular videos carry a landscape variant there instead, and the popup labels it by its measured orientation). Each size has a Download button and a Copy URL button. Not on a YouTube page? Paste any link (watch, youtu.be, Shorts, embed, live) or a bare video ID into the box instead.

Why this one:

It asks for nothing. The only permission is "activeTab", which lets the popup read the address of the tab you clicked it on. No "access your data for all websites", no content scripts, no background script, no analytics, no accounts, and the manifest declares that it collects no data.
It checks what actually exists. YouTube only creates the 1280x720 max-res file for HD uploads and custom thumbnails; for the rest, the request returns a 404 whose body is a 120x90 grey placeholder. The extension measures the real pixel width of every size and only offers the ones that are genuinely there, so you never save a grey square by mistake (this behaviour was measured on 8,664 public videos: https://thumbnailsgrabber.com/youtube-thumbnail-statistics).
Images come directly from YouTube's own image host (i.ytimg.com). Nothing passes through any other server.

Made by the team behind ThumbnailsGrabber.com, the free web-based YouTube thumbnail grabber. Need dozens of thumbnails at once? Use the bulk downloader on the site: https://thumbnailsgrabber.com/bulk-youtube-thumbnail-downloader

Open source (MIT). Thumbnails remain the copyright of their creators; download them for your own reference, previews, and research, and get permission before republishing one.