Lens is installed. Three steps and you're testing.
- Pin it. Click the puzzle icon in Chrome's toolbar and pin Thumbo Lens.
- Open the panel. Click the Lens icon. A panel opens on the right and stays open while you browse YouTube.
- Drop your thumbnail, type a search. Hit "Show me in search results" and find your video at result #2, next to the ones you compete with.
Thumbo Lens has been removed
Sorry it didn't work out. If something broke or was missing, one line to support@thumbo.ai helps us fix it for the next creator.
YouTube thumbnail preview, next to the real videos
Thumbo Lens is a free Chrome extension that puts your thumbnail and title into real YouTube search results, at the size viewers see it, before you publish. Compare up to three versions in one click and get a plain list of what to fix.
Free Chrome extension · no account · your images never leave your browser
Your thumbnail is judged next to 20 others. Test it there, not on a white canvas in your editor.
Add to Chrome - it’s freeWhat it does
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See it in real search results
Type what viewers would search. Lens opens that YouTube search and puts your thumbnail, title and channel name at result #1, #2 or #3, outlined so you can find it. Works on Home and Subscriptions too.
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Compare up to three versions
Drop or paste A, B and C. Click a version in the side panel and the search result changes instantly, so you judge each one in the same spot, next to the same competition.
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Check it at the size viewers see
Lens shows your thumbnail at real pixel size on a phone feed, desktop Home and next to a video, in dark and light mode, and reads the text on it: anything too small for a phone gets flagged, line by line.
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Know if it blends in
Lens compares your colours with the videos around yours on the page and tells you when most of them look the same as yours. It also flags text hidden under the timestamp, the wrong aspect ratio and files over the 2 MB phone upload limit.
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Steal any style
Hover any thumbnail on YouTube and click Steal style to start a new thumbnail in Thumbo from that look. You can switch the button off in the panel.
Questions
How do I preview my YouTube thumbnail before uploading?
Install Thumbo Lens, open its side panel, drop your thumbnail and type your title and a search your viewers would use. Click "Show me in search results" and Lens shows your video at result #2 of that real YouTube search, at real size, before anything is published.
Is Thumbo Lens free?
Yes. The extension is free with no account and no usage limits. Thumbo makes money only from its AI thumbnail generator, which you never have to use.
Does Lens upload my thumbnail anywhere?
No. Nothing you add in Lens is sent to Thumbo: your images, titles and settings are stored in your browser, the preview changes the YouTube page only on your screen, and the text and colour checks run on your device. The search itself runs on YouTube, like any search you type.
Can I A/B test thumbnails with it?
Lens is for testing before you publish: you compare up to three versions side by side in the real feed and pick the strongest. To split-test live traffic after publishing, use YouTube Studio’s built-in Test & Compare.
Does it work in YouTube Studio or on my phone?
Lens works on youtube.com in desktop Chrome: search results, Home and Subscriptions. It never touches YouTube Studio. For phones, the panel shows how your thumbnail looks at phone-feed size.
Free. No account, no ads, no analytics in the extension. Thumbo makes money only when you generate a thumbnail with it.