Lossy or lossless PNG compression?
Palette PNG (on by default) reduces the image to the 256 colours that represent it best and dithers the rest. For screenshots, icons, charts and illustrations this is invisible and saves 60-80%. It is the same idea that popular online PNG compressors use.
Lossless (untick Palette PNG) keeps every pixel exactly and only recompresses the data with OxiPNG. Expect 5-30% savings. Use it for images you will edit further or where exact colours matter.
When PNG is the wrong format
PNG is built for graphics. A photo saved as PNG is typically 5-10 times larger than the same photo as JPG or WebP, and no PNG compression closes that gap. If your PNG is a photo without transparency, convert it to JPG or to WebP instead.
How to compress a PNG
- Drop your images onto the box above, click it to choose them, or paste a screenshot.
- Check the settings. They are already set for this task, and you can change any of them.
- Download each image, or all of them at once as a ZIP. Click a thumbnail to compare before and after.
Images are processed as soon as you add them. Change a setting and press Apply to all again to redo the batch.
How your files stay private
Most free converters upload your file, process it on their server and send the result back - so a copy of it passes through somebody else's machine. This page does all of the work in your browser instead. The files you choose are read into memory on your own device, processed there and handed back as a download; none of their contents is transmitted. You can switch off Wi-Fi after the page has loaded and it keeps working.