Krex AI

Generation language

Default language for AI-written scripts, TTS voiceovers, and captions. You can still override per-job.

All docsCreate images

Thumbnails

Generate eye-catching thumbnails for your videos — describe what you want or start from a frame of your clip.

Create a thumbnail that earns the click. Useful for YouTube uploads and link previews where the image often decides whether anyone watches.

What it does

Thumbnails generates a still image sized for video previews. You can describe the thumbnail you want from scratch, or start from a frame of your existing clip and build on it. The result is a standalone image ready to attach to a YouTube upload or use as a link preview.

How to use it

  1. Open the Images tools and pick Thumbnails.
  2. Choose to describe a thumbnail or start from a frame of your video.
  3. Write a prompt describing the look, subject, and any text you want.
  4. Generate and review the thumbnail.
  5. Refine the prompt and regenerate until it grabs attention.
  6. Download the thumbnail and attach it to your upload.

Tips

  • Keep it bold and readable at small sizes — one clear subject beats a busy frame.
  • Starting from a real frame keeps the thumbnail honest to the video's content.
  • Run Photo Enhance on a frame first if it looks soft before building from it.
  • Use Background Remove to isolate a subject you want to feature front and center.

Ready to make one that gets clicks? Get started, or browse all docs.