Source image
Drop a PNG hereor click to browse
PNG only. Nothing is uploaded — the file stays on your device.
Re-compresses the file with no change to a single pixel.
Before / after
Drop a PNG on the left to see it compressed here.
Before
After
How PNG compression actually works, and which mode to use
PNG images can carry a fair bit of dead weight. This tool strips it in one of two ways, depending on how much size you need back.
Lossless: same picture, smaller file
A PNG stores its pixels using a general-purpose compression step (the same DEFLATE family used inside a .zip file) plus a per-row filtering choice that makes the data more compressible. Different programs make different choices about both, so a PNG saved by one tool often has real slack left in it. Lossless mode here decodes the image and re-encodes it with more careful choices, producing a file that's pixel-for-pixel identical to the original — just smaller. If a PNG has already been through a proper optimizer, there may be little or nothing left to save. That's a sign the file was already efficient, not a sign this tool has done anything wrong.
Lossy: fewer colors, a lot smaller
Most of a PNG's size comes from how many distinct colors it needs to describe. Lossy mode rebuilds the image using a reduced palette — the Colors slider sets exactly how many, from 256 down to 2 — grouping similar shades together and dithering the result so the reduction is as unnoticeable as possible. Fewer colors means a much smaller file, at the cost of some fine gradient detail. Flat-color logos, icons, and screenshots tend to hold up well even at a low color count; photos and soft gradients show the tradeoff sooner. That's exactly why the before/after preview sits right here — compare the two images visually before you settle on a number.
Why transparency doesn't break
A common failure in quick color-reduction tools is that shrinking the palette quietly flattens transparency — soft or partial see-through edges turn into a hard, opaque box. This tool's color reduction treats each pixel's alpha as part of the color it's grouping, not as an afterthought, so semi-transparent edges survive the same reduction as everything else in the image.
What this tool won't do
It only handles PNGs — not JPEG, WebP, or GIF, each of which compresses differently. And Lossy mode does change pixels: if you need a byte-for-byte or pixel-for-pixel guarantee, stick to Lossless.