Free Tools · Tester

Thumbnail Tester & Feed Preview

Your thumbnail never appears alone — it competes in a feed, at small sizes, next to other videos. Upload yours and see it exactly as viewers will, before you publish. Nothing is uploaded to any server; the preview runs entirely in your browser.

What to check in the preview

• Is your text readable at sidebar size (168px wide)? If not, it's invisible to most viewers.
• Does your subject still pop in dark mode? Dark backgrounds merge into YouTube's dark theme.
• Does the duration badge in the bottom-right corner cover anything important?
• Squint test: blur your eyes — can you still tell what the video is about?

Not happy with what you see?

If your thumbnail isn't winning the feed, generate better options: ThumbDesign creates four distinct concepts from your video link or a one-sentence description, with your face and hook. Try it free — your first generation is free, no credit card required.