How to compress
- Add one or more images: choose them, drag them in, or paste a screenshot.
- Pick a format. Keep the original format re-encodes each image as what it already is; or convert everything to JPG, WebP or AVIF; or PNG for lossless.
- Move the quality slider. The preview re-encodes the selected image and shows the new size and the saving. Hold Hold to see original to compare.
- Click Compress, then download each image or all of them as a ZIP.
Choosing a codec
| Format | Best for | Notes |
|---|---|---|
| JPG (MozJPEG) | Photos anywhere | Opens everywhere. MozJPEG is Mozilla's tuned JPEG encoder, typically 10–15% smaller than a basic encoder at the same visual quality. |
| WebP | Photos and graphics on the web | Smaller than JPEG at the same quality, supports transparency, supported by all current browsers. Some older desktop apps cannot open it. |
| AVIF | Smallest photos for the web | Often half the size of JPEG for similar quality. Slower to encode, and some apps and portals do not accept it yet. |
| PNG (OxiPNG) | Screenshots, logos, diagrams | Lossless: no detail is lost. OxiPNG finds the smallest valid PNG; large photos as PNG are big. |
What "quality 80" means
JPEG, WebP and AVIF are lossy: they throw away detail your eye is least likely to notice, mostly fine texture and subtle colour variation. The quality number controls how much. It is not a percentage of anything in particular, and the same number means different things in different encoders; quality 80 in MozJPEG and quality 80 in WebP produce different files. What matters is the result: around 75–85, photos look identical to the original at normal viewing size; from about 60, smooth areas such as skies start to show banding and edges show faint blocks or ringing. The preview lets you judge with your own eyes, which beats any rule of thumb.
Resolution matters more than quality
A phone photo is often 4,000 pixels wide or more, far more than any screen or web page shows. Halving the width and height cuts the pixel count by three-quarters, and the file size roughly with it. If an image is going on a website or into a document, resize it to the size it will be displayed (1,600–2,000 px wide is plenty for most uses) before or while compressing. That usually saves more than lowering quality, without any visible loss.
When a portal has a size limit
If you need to get under a specific size, say 200 KB, Compress to a target size does the searching for you: it tries qualities, then smaller dimensions, until the file fits. Presets cover 50 KB, 100 KB, 200 KB, 1 MB and 2 MB.
Transparency
JPEG has no transparency. If you compress a PNG or WebP with transparent areas to JPG, those areas are filled with white, and the note under the result says so. Keep transparency by choosing WebP, AVIF or PNG.
Batches
Add up to ten images free (500 with the batch licence). They all use the same settings and are processed one after another in a background worker, so the page stays responsive. The list shows each image's status; click one to preview it. When the batch is done, download individual files or everything as a ZIP. Batch licence holders can save their settings so the next batch starts the same way, and drop whole folders.
Supported inputs
JPEG, PNG, WebP, AVIF, HEIC and HEIF (iPhone photos), GIF (the first frame) and BMP open in every current browser. TIFF opens only in Safari; elsewhere convert it first. Orientation from the camera's EXIF tag is applied, so portrait photos stay upright.
Typical savings
| Starting image | Setting | Typical result |
|---|---|---|
| 12 MP phone photo, 3–5 MB JPEG | JPG quality 80, same size | 1.5–2.5 MB |
| Same photo | Resize to 2,000 px, JPG quality 80 | 350–600 KB |
| Same photo | Resize to 2,000 px, AVIF quality 60 | 150–300 KB |
| Screenshot, 1.2 MB PNG | PNG via OxiPNG | 0.7–1 MB, identical pixels |
These are typical ranges; detailed photos (foliage, gravel, fabric) compress less, simple ones (skies, studio backgrounds) more.
Troubleshooting
- The file got bigger. The original was already heavily compressed, or you converted a graphic to a photo format. Keep the original, or try PNG for graphics.
- Colours look slightly different. The original had a wide-gamut colour profile (common on recent iPhones) and the output is standard sRGB. On normal screens the difference is small.
- An image shows an error. The browser cannot decode it, usually a TIFF outside Safari or a damaged file.
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.