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FileOptimizer vs OptiPNG: catalog facts
FileOptimizer	OptiPNG
Free Free and open source under the AGPL-3.0 licence.	Free Free and open source under the zlib licence.
Windows	Windows, Command line
Lossless size reduction with no quality loss Supports a very wide range of file formats	Lossless recompression of PNG files Converts BMP, GIF, PNM and TIFF to optimized PNG
Windows only Size savings depend heavily on the file type and how it was created	Command line only, no graphical interface Lossless only, so savings are smaller than lossy tools
Downloadable app	Downloadable app
Open source	Open source
License: AGPL-3.0-or-later	License: Zlib
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked October 2, 2026

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