Preview the decision, not a dashboard.
Choose an image, enter a title, and switch between desktop and phone layouts. Light and dark surfaces are included so the same idea can be checked in two common viewing conditions.
ABOUT THE TOOL 03
Make the first impression visible.
Thumbnail Tester is a small browser tool for checking one thumbnail and one video title inside a simulated YouTube feed before publishing.
Everything happens in this browser.
The image preview is handled locally by the page. The tool does not require an account, a third-party API, or a server-side image upload.
It is not a YouTube analytics product.
It does not predict click-through rate, test a live audience, or claim that a mockup is the real YouTube interface. It is a layout check you can use before publishing.
USE THE TOOL
Start with the working page
Open the Thumbnail Tester, choose a PNG, JPG, or WEBP image, enter the title, and save the current view as a PNG when the layout looks right.