PNG Compressor

PNGs are great for graphics with sharp edges and transparency, but they're huge by default. This tool runs your PNG through pngquant + zopfli — the best-in-class lossless and near-lossless PNG optimisers — and typically returns a file 50–80% smaller. Transparency is preserved.

How PNG compression works

PNG uses lossless DEFLATE compression by default — every pixel is preserved exactly, but the result is bigger than necessary. Two techniques shrink it dramatically:

• Palette quantisation (pngquant): reduces the colour palette to 256 carefully-chosen colours. For most graphics (logos, icons, screenshots) this is visually lossless. Saves 50–70%.
• Re-encoding (zopfli): finds a more efficient DEFLATE encoding of the same pixel data. Truly lossless. Saves another 5–15%.

Combined: typical 65–80% file size reduction for graphics; 30–50% for photographic PNGs (which probably should be JPGs anyway — see Compress JPG).

When to compress PNG

1. Logos and icons: usually safe to quantise to 64 or 128 colours.
2. Screenshots: mostly flat colours, compress beautifully.
3. Illustrations: palette quantisation works great if there aren't smooth gradients.
4. Photos: consider converting to JPG or WebP instead — even compressed PNG is bigger than equivalent-quality JPG.

Quality settings

Default is 'visually lossless' (256 colours, zopfli optimised). Drop to 'small' for further savings on graphics with limited colour. 'Pristine' skips quantisation entirely and only runs zopfli — pure lossless, smaller savings, but every pixel is bit-exact.