Stenciltool does one thing well: it turns any image or text into a clean, cut-ready stencil. No account to create, nothing to install, and no images sent anywhere. Just open the page and start making.
The whole conversion — grayscale, threshold, edge detection, even the SVG vector trace — happens in your browser using the same canvas technology that powers web games. Your photo never touches a server, so it stays completely private.
Because there are no servers doing the heavy lifting, there's no cost to run a conversion — so there's no paywall and no per-image limit. Make one stencil or a thousand.
Crafters, sign painters, teachers, and hobbyists all need the same thing: a fast way to get from an image to something they can cut. The controls are deliberately simple so you can focus on the making.
The converter uses classic image-processing maths, so the same image and settings always give the same result. Predictable output means predictable cuts.
Nothing here is a black box. This is the entire pipeline, and every step runs in your browser tab:
Grayscale. Each pixel's colour is reduced to a brightness value using the standard luminance weights (29.9% red, 58.7% green, 11.4% blue).
Smoothing. If you've set it, a box blur averages each pixel with its neighbours to melt away noise and texture.
Threshold or edges. Solid mode keeps every pixel darker than your threshold; Outline mode runs Sobel edge detection and keeps the strong edges instead. Auto picks the threshold with Otsu's method.
Finishing. Invert, mirror, and transparent-background options rearrange the final black-and-white mask.
Export. PNG is written straight from the canvas; SVG is traced from the mask with a marching-squares contour walk. Both are generated in memory and saved directly to your disk.
Open your browser's developer tools while you convert if you're curious — you'll see that no image data ever appears in the network tab. That's the whole privacy model: there is simply nowhere for your image to go.