GrokThumbnails is built and maintained by an independent software developer. The goal is simple: give creators a handful of small, focused tools that answer the questions every thumbnail raises — Is it the right size? Will people be able to read it on a phone? Does it stand out next to other videos?
How our tools work
Every tool on this site runs in your web browser. When you upload an image to the preview tester, resizer, safe zone checker, colour extractor, A/B compare tool or banner checker, the image is processed on your own device using standard web technology (the HTML5 Canvas API). It is never sent to or stored on our server.
The thumbnail downloader works with the public image addresses YouTube provides for every video. We don’t download, convert or host videos or audio.
Our principles
- Free and account-free. No sign-ups, no paywalls, no download limits.
- Private by default. Your files stay on your device.
- Accurate information. Our size and spec guides are based on YouTube’s published requirements and updated when they change.
- Respect for creators. We encourage using downloaded thumbnails for learning and reference, not for copying.
How the site is funded
GrokThumbnails may show advertising to cover hosting and development costs. Ads never change how our tools work. See our privacy policy for details.
Independence
GrokThumbnails is not affiliated with, endorsed by or sponsored by YouTube, Google LLC or xAI.
Questions, ideas or a bug to report? Get in touch.