How can I convert PNG images to WebP in the browser without uploading them to a server? [closed]

You can do this entirely on the client side using the Canvas API, so the image never leaves the user’s browser.

The general approach is:

1. Read the PNG file using an <input type="file"> element.

2. Load it into an Image object.

3. Draw the image onto a canvas.

4. Export the canvas as WebP using canvas.toBlob() or canvas.toDataURL("image/webp").

This keeps user data private, avoids server-side processing, and works well in modern browsers that support WebP.

High-level logic:

- FileReader reads the image

- Image.onload draws it to a canvas

- canvas.toBlob outputs the WebP file

I built a small browser-only tool that follows this exact approach using client-side processing. Disclosure: it’s my own project. I’ve added the link in the first comment for anyone who wants to see a working example.

Disclosure: I built a small browser-only converter that uses this same client-side Canvas approach. Example implementation: https://toolbly.com/file-converters/png-to-webp