Will I see a difference?

At 256 colours, rarely on graphics and screenshots. Smooth gradients and photos can show banding, so use the compare view.

Is transparency kept?

Yes. Transparent and semi-transparent pixels are kept through colour reduction.

Lossless can only find better packing. Most savings in PNG come from having fewer colours.

No. Compression happens in your browser with WebAssembly, so nothing is sent to a server.

Compress PNG

Make PNGs much smaller by reducing colours, with transparency kept.

Runs on your device. Nothing is uploaded.

Add PNGs
Drop files, or click to browse.
Set the colours
256 is usually invisible. Go lower for flat graphics.
Or stay lossless
Turn on Lossless to keep every pixel and only pack the file tighter.
Compress and download
Press Compress, then save each file or a ZIP.