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About this tool
Generate high-converting, viral YouTube thumbnails using AI. Answer a few questions about your video, generate the layout, add an optional headline woven into the AI prompt, and download.
The Viral Thumbnail Maker generates four AI thumbnail concepts from your video topic by combining it with one of eight style presets, one of six colour palettes and your optional headline text into a single image prompt, then upscaling each result to YouTube's recommended 1280x720. You get four different seeds per run so you have real alternatives to compare rather than one take, and the last 20 images stay in your browser's local storage. It is a fast way for creators to get past the blank canvas, not a replacement for a designer on a channel that depends on its look.
Open Viral Thumbnail Maker on AltFTool — it loads instantly in your browser.
Describe the video in the 'What is your video about?' box, and optionally type a headline into 'Text on thumbnail'.
Pick one of the eight Visual Style tiles (Gaming, Tech / Coding, Finance, Storytelling, Education, Fitness, Food, Travel) and one of the six Color Theme swatches, then press 'Generate AI Thumbnails'.
Four seeded takes appear under 'Your AI Thumbnails' — press Download on one to save it as thumbnail_1.jpg at 1280x720, press Regenerate for a fresh set, or reopen the last 20 under Recent Thumbnails.
Each generation issues two parallel batches with independent random seeds, so you are usually choosing between four takes instead of regenerating one image until it lands. If the third-party image service drops a request, you may get fewer and can hit Regenerate for the rest.
Picking Finance plus Red and Black writes specific composition and lighting language into the prompt for you, which is the part most people get wrong when prompting by hand.
Every image is drawn onto a 1280x720 canvas with high-quality smoothing and saved as JPEG, so it uploads without being rescaled or rejected.
1280x720 pixels at 16:9, which is exactly what this tool exports. It saves as JPEG at high quality, comfortably inside YouTube's thumbnail file-size limit, and anything smaller than 1280 wide gets upscaled by YouTube and looks soft in the sidebar.
Not quite. The text prompt built from your topic, style, palette and headline is sent to a third-party image generation service, and the returned image is then upscaled and encoded locally. Your history of the last 20 thumbnails is stored only in your own browser.
You can type a headline and it is written into the prompt as bold stylised thumbnail text, which the image model renders as part of the artwork. AI-rendered lettering can come out misspelled, so for anything you are publishing, set the text in a proper editor over the generated background.
Eight styles — gaming, tech, finance, storytelling, education, fitness, food and travel — and six palettes including cyan and purple, red and black, yellow and dark, neon green, warm orange and pink gradient, giving 48 combinations before you change the topic or headline.