Smaller images load faster, rank better and cost less to host. Here is how to get the most out of OptiMiZero, from a single photo to a whole folder.
The quick way
- Open the optimizer and drop your images onto the dashed box. You can also click Choose images, pick a folder, or paste a screenshot with Ctrl+V or Cmd+V.
- Wait a moment. Each image shows how much it shrank, with a green badge for the percentage saved.
- Click Download beside an image, or Download all (ZIP) to get every optimized file at once.
Smart mode and Custom mode
Smart is the default. For JPG it re-encodes at a quality that is never higher than the original, so files only get smaller. For PNG it compares lossless and reduced-color versions and picks the smaller one that still looks the same. Photos saved as PNG are offered as WebP, which is usually far smaller. Animated files are left untouched rather than flattened by accident.
Custom gives you a quality slider, the number of PNG colors and a lossless PNG switch. Use it when you know exactly what you need.
Resize and target size
Enter a max width to scale large images down. Photos straight from a phone are often 4000 pixels wide, far more than a web page needs. Enter a target size in KB when a form or platform demands a limit. The tool searches for the highest quality that fits and, if needed, reduces dimensions in small steps. If it cannot reach the target it tells you and gives you the closest result.
Which format should I choose?
| Format | Best for | Notes |
|---|---|---|
| JPG | Photos | Works everywhere. No transparency. |
| PNG | Logos, screenshots, graphics with sharp edges | Supports transparency. Large for photos. |
| WebP | Almost anything on the web | Smaller than JPG and PNG, supports transparency, supported by all current browsers. |
| AVIF | Photos when every byte counts | Smallest files, slower to create. Supported by current browsers. |
| GIF | Short animations | Stays GIF. For long clips, a video is much smaller. |
| SVG | Icons and illustrations | Cleaned and minified without changing how it looks. |
Privacy and metadata
Your files stay on your device. Metadata such as GPS position, camera model and edit history is removed by default, which also saves a few kilobytes. For JPG you can keep it. The image orientation is always preserved.
Tips for a faster website
- Resize to the largest size the image is actually shown at, then compress.
- Use WebP for most images and keep JPG as a fallback only if you must support very old browsers.
- Do not compress the same file repeatedly. Always start from the original.
- Check the result with the Compare slider before replacing a file on your site.
Troubleshooting
- “This image could not be read.” The file is damaged or in a format your browser cannot open, such as HEIC. Convert it to JPG first.
- “Too large to process.” Images above about 80 megapixels exceed what a browser can handle. Resize them first.
- The file did not shrink. It was already well optimized, so the original is returned unchanged.
- Slow on a phone. Large batches use your device’s processor. Try fewer files at a time.
Still stuck? Tell us what happened and which browser you use.