Convert WebP to PNG in Firefox: 3 Methods That Work Without Extensions

Firefox users run into WebP files constantly — from stock photo sites, social media downloads, and web screenshots. The problem is that many image editors and older software still expect PNG. If you are using Firefox and need to convert WebP to PNG, you have several options that do not require installing a browser extension.

Method 1: Use a browser-based converter (fastest)

The quickest way to convert WebP to PNG in Firefox is to use a browser-based tool like FreePNGConvert. Because the conversion runs entirely in your browser’s JavaScript engine, it works the same in Firefox as it does in Chrome or Safari.

Steps:

1. Open freepngconvert.com in Firefox.
2. Drag your .webp file onto the converter area, or click to browse.
3. The file is decoded and converted to PNG in your browser — no upload, no server.
4. Click Download to save the .png file to your computer.

The entire process takes under two seconds for most images. Because the file never leaves your device, this is also the most private option. For more on why that matters, see our safe WebP to PNG converter guide.

What about transparency? Firefox’s Canvas API — which powers the conversion — fully supports the alpha channel. Transparent backgrounds in your WebP file are preserved in the PNG output. See our detailed transparent background conversion guide for specifics.

Method 2: Save images directly from Firefox as PNG

Firefox has a lesser-known behavior: if you right-click an image on a web page and select “Save Image As…”, Firefox sometimes saves it in its original format (WebP). But there is a workaround using Firefox’s screenshot tool:

1. Right-click the WebP image on the page.
2. Select “Take Screenshot” from the context menu.
3. Click on the image element to isolate it.
4. Click the Download button to save it as a .png file.

This method crops the image to its visible dimensions and saves it as PNG. The downside is that it captures the screen-rendered version, not the original file data. For high-resolution or transparent images, Method 1 is more reliable because it preserves the full pixel data and alpha channel.

For a comparison of format quality differences, see our WebP vs PNG quality guide.

Method 3: Use Firefox DevTools for manual conversion

If you are comfortable with the browser console, you can convert WebP to PNG without any external tool:

1. Open a new tab in Firefox and press F12 to open Developer Tools.
2. Go to the Console tab.
3. Paste this code:

const input = document.createElement('input');
input.type = 'file';
input.accept = '.webp';
input.onchange = async (e) => {
  const file = e.target.files[0];
  const img = new Image();
  img.src = URL.createObjectURL(file);
  await new Promise(r => img.onload = r);
  const canvas = document.createElement('canvas');
  canvas.width = img.naturalWidth;
  canvas.height = img.naturalHeight;
  canvas.getContext('2d').drawImage(img, 0, 0);
  canvas.toBlob(blob => {
    const a = document.createElement('a');
    a.href = URL.createObjectURL(blob);
    a.download = file.name.replace('.webp', '.png');
    a.click();
  }, 'image/png');
};
input.click();

4. Select your .webp file in the file picker.
5. The PNG downloads automatically.

This works because Firefox’s JavaScript engine supports the Canvas API and WebP decoding natively. It is the same technology that powers FreePNGConvert, just without the user interface.

Do you need a Firefox extension?

Several Firefox extensions promise automatic WebP-to-PNG conversion, such as “Save webp as png or jpeg.” These extensions intercept your downloads and convert files in the background. While convenient, they come with trade-offs:

• Permissions: Extensions that intercept downloads need broad permissions to read your browsing activity and file downloads.
• Maintenance: Many free extensions are abandoned after a year or two and may break with Firefox updates.
• Quality: Some extensions use lower-quality conversion settings or strip metadata.
• Performance: Background interception can slow down your browsing, especially on image-heavy pages.

For most users, a dedicated browser-based converter like FreePNGConvert offers the same result with better transparency about what happens to your files. No permissions, no background processes, no extension updates to manage.

Firefox version requirements

All three methods above work in current Firefox versions. Specifically:

• Canvas API support: Firefox 28+ (released 2014)
• WebP decoding: Firefox 65+ (released January 2019)
• canvas.toBlob(): Firefox 18+ (released 2013)

If you are running Firefox 65 or later — which is virtually every current installation — WebP decoding and PNG export work out of the box. No flags to set, no about:config changes needed.

Firefox-specific tips

Handling large WebP files

Firefox handles large images well, but very large files (over 50 megapixels) may hit memory limits in the Canvas API. If the conversion appears to stall on a large file, try closing other tabs to free memory.

Preserving color profiles

Firefox supports ICC color profiles in both WebP and PNG. When you convert using the Canvas API, the color profile from the WebP source is carried over to the PNG output. This means your converted PNG will look the same as the original WebP — no color shift. For details on quality preservation, see our guide on converting WebP to PNG without losing quality.

Converting animated WebP

The Canvas API captures a single frame. If your WebP file is animated, the conversion will save the first frame as a static PNG. This is a limitation of the PNG format itself, which does not support animation.

Common questions

Does FreePNGConvert work offline in Firefox?

Yes. After the initial page load, the service worker caches all assets. You can convert files even without an active internet connection. For more details, see our offline conversion guide.

Is the conversion quality the same in Firefox as in Chrome?

Yes. Both browsers use the same Canvas API to decode WebP and encode PNG. The output is pixel-identical regardless of which browser you use.

Can I convert multiple WebP files at once?

Currently, the converter processes one file at a time. For batch conversion, you would need a desktop tool like ImageMagick (convert input.webp output.png) or a command-line script.

Why does Firefox save images as WebP in the first place?

Many websites serve images in WebP format because it provides better compression than PNG or JPEG. When you right-click and save an image in Firefox, it saves the file in the format the server provided. This is not a Firefox setting you can change — it reflects how the website delivers its images. For more context, see our guide on why images save as WebP.

---

Last updated: 2026-06-05