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pngcrush vs OptiPNG: catalog facts
pngcrush	OptiPNG
Free Free to use, modify, and redistribute under the license described with its source.	Free Free and open source under the zlib licence.
Windows, Linux, Command line	Windows, Command line
Tries compression levels and PNG filters to reduce file size Can remove or add ancillary PNG chunks	Lossless recompression of PNG files Converts BMP, GIF, PNM and TIFF to optimized PNG
It is a command-line application.	Command line only, no graphical interface Lossless only, so savings are smaller than lossy tools
Downloadable app	Downloadable app
Open source	Open source
License: libpng license equivalent	License: Zlib
Not stated if an account is needed	No account needed
Not stated if it works offline	Works offline
Official website Full listing and sources Checked October 8, 2026	Official website Full listing and sources Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.