Thumbnail preview tool · runs in your browser
See your thumbnail where viewers will see it.
Drop in up to four thumbnails, add your title and channel name, and Thumbframe shows them in home-grid, search, mobile and "up next" mockups, in light and dark themes. It also flags text that is too small to read, low contrast, and anything hidden under the duration badge.
Open the tool Nothing is uploaded. Your images stay on this device.
2 · Preview preview mockup
3 · A/B compare
4 · Legibility checks
Pricing
Free
$0
- 1 thumbnail at a time
- All mockups, both themes
- All legibility checks
- PNG export with watermark
Pro
$19 one-time
- Compare up to 4 thumbnails side by side
- Clean exports, no watermark
- Use on up to the activation limit of your key
- Future updates included
Privacy
Thumbframe is a static page. Your images, title and channel name are processed in your browser with the Canvas API and are never uploaded. There is no analytics script on this page. The only network request the tool makes is when you activate or re-check a Pro license key: the key (and a generic instance name) is sent to Lemon Squeezy's license API to confirm it is valid. The activation result is stored in your browser's localStorage.
FAQ
Is this an official YouTube tool?
No. Thumbframe is independent and not affiliated with YouTube or Google. The mockups are generic approximations of common video-feed layouts, labeled as previews, and do not use any platform logos.
Are my thumbnails uploaded anywhere?
No. Everything happens locally in your browser. You can even use the page offline once it has loaded.
How accurate are the legibility checks?
They are heuristics: a contrast estimate from pixel luminance, an edge-based guess at text size, and a check of the corner where the duration badge sits. Treat warnings as prompts to look again, not verdicts.
What size should my thumbnail be?
Use 1280×720 (16:9). Other ratios are center-cropped in the mockups.
How does the license work?
Buy once for $19, paste the key, click Activate. The key is checked with Lemon Squeezy and remembered in this browser. Refunds follow the Curiofy refund policy.