Why WebP?
WebP handles both photos and graphics well and supports transparency, so it can replace PNG on websites at a fraction of the size. A transparent logo or illustration that is 300 KB as PNG is often 50–100 KB as WebP at high quality, and a photo saved as PNG shrinks even more.
Quality setting
For graphics with text and sharp edges, use quality 85–95 to keep edges crisp. For photos, 75–85 is plenty. The preview shows the size and lets you compare.
Compatibility
All current browsers display WebP, as do Windows 11, macOS, iOS and Android. Some older desktop applications and email clients do not; keep the PNG for those.
Transparency
Alpha transparency is preserved, including soft edges and shadows.
PNG and WebP compared
| Feature | PNG | WebP |
|---|---|---|
| Compression | Lossless | Lossy or lossless |
| Transparency | Yes | Yes |
| Web file size | Larger | Smaller |
| Desktop app support | Universal | Good, not universal |
Step by step
- Add your PNG files: choose them, drag them onto the page, or paste.
- Set the quality; 85 is a good default.
- Click Convert to WebP.
- Download each file, or all of them as a ZIP. File names stay the same with the new extension.
Without this tool
Windows and macOS do not export WebP from their built-in apps; image editors such as GIMP, Photoshop (2022 and later) and Affinity do. This tool does it in the browser without installing anything.
Troubleshooting
- A file shows an error. It may not really be PNG: files are sometimes renamed without being converted. The tool reads the file's contents, not its name, and says what it found.
- The converted file is larger. That is expected when going to a less efficient or lossless format; it is not a fault.
- Colours shift slightly. Wide-gamut originals are converted to standard sRGB, which every screen shows consistently.
For websites
Replacing PNG illustrations, icons and screenshots with WebP is one of the quickest ways to make a website load faster. Keep the PNG originals as your masters, upload the WebP versions, and most site builders and content management systems will serve them as-is. For photos currently stored as PNG the savings are even larger.
Lossless WebP
At the highest quality setting WebP is visually indistinguishable from the PNG; for pixel-perfect needs keep the PNG.
Compatibility checks
Before switching a whole site to WebP, check where else the images are used: email newsletters and some social sharing previews may still need PNG or JPG. Keep both versions if your platform cannot fall back automatically.
Private by design
The image never leaves your device. It is decoded in your browser, processed in a background worker by open-source codecs compiled to WebAssembly (MozJPEG, libwebp, libavif and OxiPNG, via the jsquash project, plus pica for resizing) and handed back as a download. There is no upload, no account and no server copy to delete. You can confirm it in your browser's developer tools: the Network tab shows the page's own files and the codec files loading, and nothing carrying your image. After the first visit the tools work offline.