Create WebP Alpha Mask
Render the alpha channel as a grayscale mask (white=opaque). Runs entirely in your browser, so your data never leaves your device.
Drop a file here, or click to browse
Files never leave your device
Output
The result appears here as you type.
How to use Create WebP Alpha Mask
- 1. Load a WebP with transparency. Drop or browse for a WebP that has an alpha channel, such as a sprite or cutout logo. Images without transparency will just produce a flat white mask.
- 2. Review the alpha mask. The tool renders the alpha channel on its own as a grayscale image, where fully opaque areas show as white and fully transparent areas show as black.
- 3. Download the mask. Download the grayscale mask, useful for compositing tools, shaders or debugging exactly which parts of the source image are transparent.
When to use Create WebP Alpha Mask
Create WebP Alpha Mask isolates just the transparency data from an image and shows it as a grayscale picture, white for opaque and black for see-through. It is for inspecting or reusing an image's alpha channel directly.
- Debugging an unexpected transparency edge. A sprite shows an odd fuzzy edge in a game engine, and rendering its alpha channel as a grayscale mask reveals exactly where the transparency gradient is uneven.
- Reusing a shape as a mask elsewhere. A cutout icon's silhouette needs to become a reusable mask in a different compositing tool, and extracting the alpha channel as a grayscale image provides exactly that shape.
- Verifying an export kept its transparency. After exporting a graphic from a design tool, checking its alpha mask confirms the intended transparent regions actually made it into the final WebP file.
Examples
Alpha to mask
Input
sprite.webp with transparency
Output
grayscale mask where white is opaque and black is transparent
About the Create WebP Alpha Mask tool
Create WebP Alpha Mask runs as plain JavaScript in your browser tab, with no server behind it. Render the alpha channel as a grayscale mask (white=opaque). Whatever you put in stays on your device from start to finish.
The tool is part of EditSafely's WebP Tools section, 57 single-purpose utilities built around the same idea: open the page, get the result, keep your data to yourself.
There is nothing to configure. Provide the input and the result appears on its own. The finished file is put together in browser memory and saved with the Download button, so it never touches a server on the way to your disk. A worked example further down the page shows exactly what the tool produces for a real input.
That local-first design has practical benefits beyond privacy. The tool keeps working on a flaky connection once the page has loaded, results are instant because nothing round-trips to a server, and it is safe to use with confidential material.
Frequently asked questions
Does Create WebP Alpha Mask cost anything?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Are my files uploaded to a server?
No data leaves your device. The whole tool is JavaScript that runs inside your browser tab, so there is no upload, no server-side processing and no log of what you did. If you disconnect from the internet after the page loads, it keeps working.
Which files does Create WebP Alpha Mask accept?
It accepts WebP images. There is no file size cap imposed by a server; very large files are limited only by your device's memory.
Do I need to sign up or install anything?
Nothing to install and no account needed. Open the page in any up-to-date browser, including on a phone or tablet, and the tool is ready.
How do I save the output?
Click the Download button once the result is ready. The file is built in your browser's memory and handed straight to your downloads folder, without passing through a server.