ThumbBlitz

ThumbBlitz is a free Roblox thumbnail maker that runs in your browser. Start with a gameplay screenshot you already captured, then add a headline in one of 8 styles, place stickers and choose a backdrop. You can drag the headline or stickers on the canvas, switch export sizes, and download a PNG at 1920×1080, 1280×720 or 512×512. The tool requires no sign-up and adds no watermark. Your image stays in the browser and is not uploaded to a server. It is not an AI generator, so the cover is built from your own screenshot rather than invented pixels. The site also offers template pages, per-game thumbnail makers and guides, plus 3 backdrop variants for A/B testing.