What it does
OptiPNG optimizes PNG files without information loss, converts several raster formats to optimized PNG and checks PNG integrity.
Supply files to the CLI and choose optimization level or filter trials. Improved PNGs are replaced in place by default; use -keep for backups or -dir for another destination. Converted BMP, GIF, PNM or TIFF inputs receive .png output names, while -out accepts exactly one input. Use -simulate to run trials without writing. Treat -clobber carefully because it permits replacing existing outputs and backups. Error recovery with -fix can increase size when integrity requires it. The project uses the ZLIB open-source licence.
Strengths
- Lossless PNG recompression
- PNG integrity checking and correction
Watch out for
- Default PNG optimization replaces improved inputs; -clobber can also replace existing output and backup files.
Best for
- Optimizing PNG assets
Sources
- OptiPNG Home Page (Oct 26, 2026)
- OptiPNG in-place optimization and destination/backup controls (Oct 26, 2026)
- OptiPNG stable release and ZLIB licence (Oct 26, 2026)