Compress PNG images
Make PNG screenshots, logos and graphics smaller while keeping them PNG and keeping transparency. All processing is local.
Files never leave your deviceNeed more settings? Open the full Compress Image tool.
How to compress a PNG
- Drop your PNG files onto the box above, or paste a screenshot.
- Keep Output format on Same as original to stay with PNG.
- Set the Quality slider. Lower values use fewer colours and give smaller files.
- Press Compress, compare with the before/after slider, and download.
How PNG compression works
PNG is lossless, so it cannot throw away detail the way JPG does. There are two ways to make one smaller, and this tool uses both:
- Colour quantisation. Most screenshots, logos and illustrations use far fewer distinct colours than the 16 million a PNG can store. Reducing the image to a carefully chosen palette of up to 256 colours often cuts the size by 60 to 80 percent with little visible change. This is the same idea that popular services such as TinyPNG use.
- Optimised packing. The image is then re-compressed with oxipng, which tries several filter and compression strategies and keeps the smallest.
At quality 100 the palette step is skipped, so the image stays pixel-perfect and only the packing is optimised.
Transparency stays intact
Transparent and semi-transparent pixels are part of the palette, so logos, icons and UI elements keep their soft edges and drop shadows. That makes this the right tool when the output has to remain a transparent PNG, for an app, a game or a design file.
When to use a different format
PNG compression works best on graphics. For photographs saved as PNG, a palette cannot capture smooth gradients, so the saving is small or the image starts to look banded. In that case:
- convert to JPG for the smallest universally supported file;
- convert to WebP to keep transparency with a much smaller file;
- or compress JPEG if the image is already a JPG.
No upload
The PNG encoder, quantiser and oxipng all run as WebAssembly in your browser. Your images are processed on your device and never leave it, and the tool keeps working offline after the first visit.
Frequently asked questions
How do you compress a PNG without changing the format?
The tool reduces the number of colours to a well-chosen palette (the same idea as TinyPNG) and then re-packs the file with oxipng. Lower quality means fewer colours and a smaller file.
Is the transparency kept?
Yes. Transparent and semi-transparent pixels are kept in the palette, so logos and icons keep their soft edges.
Why did my photo PNG not shrink much?
Photos have smooth gradients that need many colours. For a photo, converting to JPG or WebP gives a far smaller file than any PNG optimisation.
Are my files uploaded anywhere? How can I check?
No. The PNG compressor runs entirely in your browser using JavaScript and WebAssembly, so your files never leave your device. You can verify it: open your browser's DevTools (F12, or Cmd+Option+I on a Mac), switch to the Network tab, tick "Preserve log", clear the list and process a file. You will only see requests for this site's own static files, never one that carries your data. You can also turn on "Offline" in the Network tab (or disconnect from the internet) once the page has loaded, and the tool keeps working.
Does it work offline?
Yes. After your first visit a service worker saves the tool to your device, so it opens and works without a connection. Only advertising needs the internet; the processing never does.