Hit 20 KB, 100 KB or any limit. Runs on your device.
You pick a limit, such as 100 KB. The tool lowers the picture's quality a little at a time until the file fits. If that is not enough, it also makes the picture smaller in pixels, so it still looks clean instead of blocky. Expect results a few KB under your limit, because the tool keeps the best version that fits. Very small limits give smaller pictures: a 4000 by 3000 photo at 20 KB comes out around 1000 by 750 pixels. It cannot work when the limit is tiny for a detailed photo. The picture never goes below 200 pixels on its longest side, so you get the smallest file possible and a button to raise the limit.
PNG is lossless. It stores every pixel exactly, so it has no quality setting to turn down, and the only way to shrink one in a browser is to cut its pixel dimensions. That rarely reaches a tight limit. So when you add a PNG and leave the format on Auto, it is saved as a JPEG. If the PNG has transparent areas it is saved as WebP instead, because JPEG cannot store transparency. The result row tells you when either happened. If you choose JPEG yourself for a transparent image, the clear areas are filled with white. Some browsers cannot save WebP: there, Auto uses JPEG and says so, and choosing WebP yourself shows a message asking you to pick JPEG. Nothing is switched behind your back. This tool does not make PNG files smaller while keeping them PNG. Screenshots with small text can show faint halos around the letters once they are JPEGs at a low size, so give those a higher limit.
A compressed file is drawn fresh from the pixels of your image, so it carries none of the original's metadata: no GPS location, camera model or capture date. The rotation flag that phones store is applied first, so a portrait photo stays upright. There is one exception. If your image is already under the limit, and you have not asked for a different format or a smaller size, you get your original file back untouched instead of a worse copy. That file still contains whatever metadata it had, and the result says so. The same happens in quality mode when saving again would make the file bigger.
The work is done by your browser's own image code, on a canvas inside this tab. There is no upload step and no server that receives pictures. The page counts visits with Google Analytics; those counts say which tool was opened and use rough groups such as 1 to 10 MB, never a file name, an image or an exact size. Because everything runs on your device, its memory sets the limits: up to 50 images in a batch, about 500 MB in total on a computer or 150 MB on a phone, and single images up to 100 megapixels, or 50 on a phone. Images are processed one at a time to stay inside that, and a very large batch may pause and ask you to download what is finished before it goes on.
The limit is a ceiling. The tool keeps the highest quality that fits at or under it, and quality moves in steps, so a 100 KB target usually lands a few KB below 100. A file that is over the limit is never presented as if it met it.
Yes. Choose Custom and type any size from 1 KB to 50 MB. Below about 20 KB a photo has to lose pixels as well as quality, and the tool stops shrinking at 200 pixels on the longest side. If it cannot reach your number it shows the smallest size it managed, for example 3 KB against a 1 KB target, and offers to raise the limit.
Your limit was too small for the original pixels. The tool first lowers quality to a clean level, then shrinks the picture in proportion, never below 200 pixels on the longest side. The result shows both sizes, such as 4000 × 3000 → 1000 × 750 px. A higher limit keeps more pixels, and Keep original dimensions stops the shrinking.
It stops the tool from shrinking the picture, so only quality is lowered to reach your limit. The pixel size stays, for example 3000 × 2000, but a small limit such as 100 KB then forces a very low quality and the result looks blocky. Leave it off for a cleaner picture at the same file size.
Partly. Once this page has loaded, compressing an image and downloading it need no connection. Two things do: the Try a sample button fetches a 1.4 MB sample photo, and the first Download all (.zip) loads a small extra file. Do either once while you are online.
Up to 50 images at a time. A batch can total about 500 MB on a computer or 150 MB on a phone, and one image can be up to 100 megapixels, or 50 on a phone. These come from how much memory a browser tab can use, not from an account or a paid plan.
PNG has no quality setting, so it cannot be squeezed down to a chosen size. With the format on Auto, a PNG is saved as JPEG, or as WebP when it has transparent areas. Making a PNG smaller while keeping it a PNG is not something this tool does.