ThumbnailPreview

See your thumbnail in the feed — before you upload.

Drop in your thumbnail and preview it against real competitors in Home, Search and Suggested, on desktop and mobile. Free, instant, and 100% private: nothing leaves your browser.

No competitor videos loaded yet.

Preview your thumbnail in 3 steps

  1. Pick a niche pack — or import your own competitor list (CSV).
  2. Add your thumbnails with “＋ My thumbnails”, paste one (Ctrl/Cmd+V), or drop an image anywhere.
  3. Compare Home, Search and Suggested on desktop and mobile.

Import your competitors

Load the videos you want to compare against from a CSV file. Importing replaces the current competitor list; your own thumbnails are never touched.

Example of a valid file:

videoUrl,title,channel
https://www.youtube.com/watch?v=dQw4w9WgXcQ,Never Gonna Give You Up,Rick Astley
https://youtu.be/jNQXAC9IVRw,"Me at the zoo, remastered",jawed

Data in another format? Copy the prompt above, paste it into ChatGPT, Claude or any assistant together with your file, and you'll get back a ready-to-import CSV.

How it works

  1. 1

    Pick your competition

    Choose a niche pack of real videos, or import your own competitor list from a CSV file.

  2. 2

    Add your thumbnail

    Upload, paste (Ctrl/Cmd+V) or drag & drop your design. Give it a title and your channel name.

  3. 3

    Compare everywhere

    Flip through Home, Search and Suggested on desktop and mobile, reshuffle the feed, and see if your thumbnail wins the click.

Why preview a thumbnail before uploading?

Click-through rate decides how far YouTube spreads your video, and the thumbnail drives most of that decision. But a design that looks great full-screen in your editor competes in the wild at a fraction of the size, sandwiched between rival videos, often in dark mode.

Previewing your thumbnail in a realistic feed shows you what viewers actually see — how it reads at small sizes, whether it stands out next to the competition, and whether title and image work together — before the upload is live and the first impressions are spent.

YouTube thumbnail specs

Resolution
1280 × 720 px (minimum width 640 px)
Aspect ratio
16:9
Max file size
2 MB
Formats
JPG, PNG, WebP (non-animated)

Keep faces and text away from the bottom-right corner — the video duration badge covers it. Test readability at small sizes: most impressions happen in feeds, not full screen.

Frequently asked questions

Is my thumbnail uploaded anywhere?

No. Everything runs in your browser. Your images, titles and lists never leave your device — there is no server to send them to.

How do I test my YouTube thumbnail before uploading?

Add your thumbnail image, pick a niche pack or import competitor videos, and compare how your design looks in Home, Search and Suggested feeds on desktop and mobile.

Can I compare against real videos in my niche?

Yes. Built-in niche packs contain real competitor videos, or you can import your own list — a simple CSV with video URL, title and channel.

What size should a YouTube thumbnail be?

1280 × 720 pixels with a 16:9 aspect ratio, under 2 MB, as JPG, PNG or WebP. The mock renders your image exactly like YouTube would.

Are the view counts and dates real?

Competitor titles and thumbnails are real; view counts, ages and search snippets are simulated. They stay stable per video so comparisons remain fair, and reshuffle regenerates them.

Does it work for mobile thumbnails?

Yes — toggle Desktop / Mobile to preview inside a phone-sized YouTube layout, where thumbnails render even smaller and details matter more.

Is this tool free?

Completely free, no account needed. The site is supported by a few clearly-placed ads.

Why do thumbnails matter so much?

Along with the title, the thumbnail is the main thing a viewer sees before deciding to click. Higher click-through rates tell YouTube to show your video to more people.

Nothing leaves your browser

This tool has no backend. Your images are handled with local browser APIs, stored only in your browser's own storage, and are gone the moment you clear it. The only outside requests are for competitor thumbnails, loaded directly from YouTube's public image servers.