Compress PNG images

Reduce PNG screenshots, logos and transparent graphics by cutting them to a smart colour palette and recompressing with OxiPNG, all inside your browser.

Why fewer colours make a smaller PNG

PNG is lossless: it predicts each pixel from its neighbours and stores the differences with DEFLATE (the zip algorithm). The fewer distinct colours an image has, the more exact repeats DEFLATE finds. A quantiser picks the 256 (or fewer) colours that best represent your image, which is invisible on most UI and logo art and can shrink files dramatically. Try it:

Sample
Colour budget

0 distinct coloursPNG: 0 B

These byte counts come from your browser’s own PNG encoder, run live. PNG’s filters and DEFLATE find repeats; fewer colours mean more repeats. A flat logo barely changes when you cut its colours, while the gradient turns into visible bands. That is why this site’s PNG mode picks a palette with a quantiser and then lets OxiPNG squeeze the result.

Which setting for which image

ImageColoursWhy
App screenshots, UI mockups256Text stays crisp; gradients in UIs are usually short.
Logos, icons, flat illustrations64 or 16Few real colours to begin with; the palette is nearly exact.
Product cut-outs with soft shadows256Keeps smooth alpha edges. WebP or AVIF can be smaller still.
Images you’ll edit again, pixel art, medical or scientific imagesLosslessEvery pixel value is preserved exactly.
Photosn/aUse JPG or convert PNG to WebP.

Questions

Is PNG compression lossless?

OxiPNG’s recompression is lossless. The optional colour reduction is lossy: it maps the image to a palette of 256 or fewer colours. Choose “Lossless” in the colours menu to keep every pixel exactly.

Will transparency be kept?

Yes. Palette PNGs keep alpha, including semi-transparent edges, so cut-outs and logos stay clean.

Why is my PNG photo still large?

PNG is designed for graphics. A photo has millions of subtly different colours, which PNG can’t compress well. Convert photos to JPG, WebP or AVIF for a much smaller file.

How is this different from TinyPNG?

The approach is similar (reduce colours with a quantiser, then recompress), but here it all runs locally in your browser, so nothing is uploaded and there is no monthly file limit.