What it does
pngquant is a command-line PNG compressor and library using palette generation and dithering while retaining alpha transparency.
Run the CLI on selected PNGs, including multiple files in one command. Default output names gain -or8.png or -fs8.png; the extension can be changed. Set a minimum and maximum quality from 0 to 100 and choose a speed trade-off. If the result misses the minimum, no output file is saved and exit status is 99; a stdout pipeline instead receives the original 24-bit image. This is lossy palette conversion despite retained alpha transparency. Source is available under GPL or a commercial licence.
Strengths
- Alpha transparency support
- Command-line integration for repeated processing
Watch out for
- Compression is lossy
Best for
- Reducing PNG delivery copies
Sources
- pngquant — lossy PNG compressor (Oct 26, 2026)
- pngquant CLI outputs, quality rejection and licensing (Oct 26, 2026)