shortkakesFree YouTube Thumbnail Tester.
The honest thumbnail tester creators actually use. Upload a thumbnail or paste a YouTube link — get a 0–100 Viral Score, an AI roast, and 3 fixes before you upload.
3 free per day · No sign-up
What we look at
- Readability at 120px
- Curiosity gap between title and image
- Face and emotion presence
- Text restraint — 3 to 5 words, high contrast
- Color pattern-interrupt vs the feed
The YouTube thumbnail tester, minus the guesswork
Most thumbnail testers show you a mockup and call it a day. Ours actually reads the image — faces, text density, contrast, curiosity gap — and tells you what to change. It's free, it takes 8 seconds, and you don't need an account.
Want to compare two thumbnails head-to-head? Try the free A/B test. Just need to download a video's existing thumbnail? Grab it here.