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SPECIFICTION
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pngcrush

pmt.sourceforge.io

Free plan WindowsmacOSLinux
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Spec score 8.3 #24 of 85 in Image Compression Software

What it is

pngcrush is a free command-line utility for losslessly optimizing PNG files. It tries compression levels and PNG filter methods to reduce the size of a file’s IDAT datastream, and supports batch processing. Its chunk controls can remove unwanted ancillary chunks or add gAMA, tRNS, iCCP, and textual chunks. The supported format is PNG; image resizing and API access are not provided. pngcrush runs from MSDOS, UNIX, or Linux command lines, and the maker links to precompiled Windows binaries for an MSDOS window. Source code is available from SourceForge and the pmt git repository, with libpng and zlib included in the distribution. The maker permits use, modification, and redistribution without a fee; the license is equivalent to, but not identical with, the libpng license. Build choices matter: the maker warns about overflow vulnerabilities when compiling with certain older unpatched libpng versions, and says a build statically linked with the supplied zlib is believed to avoid a particular double-free bug. The SourceForge files page lists pngcrush-1.8.11.tar.xz as the latest version. Free graphical applications that embed pngcrush are also noted by the maker.

Spec sheet

Purpose
pngcrush optimizes PNG files by trying compression levels and PNG filter methods to reduce the IDAT datastream size.Read 8 Oct 2026 · pmt.sourceforge.io
Free plan
YesRead 20 Sep 2026 · pmt.sourceforge.io
License
The maker says pngcrush is open source and may be used, modified, and redistributed without paying a fee; its license is equivalent but not identical to the libpng license.Read 8 Oct 2026 · pmt.sourceforge.io
API access
NoRead 20 Sep 2026 · pmt.sourceforge.io
Batch processing
YesRead 20 Sep 2026 · pmt.sourceforge.io
Build caveat
The maker warns that compiling with an unpatched libpng earlier than 1.2.7 or 1.0.17 leaves the program vulnerable to overflow conditions fixed in August 2004.Read 8 Oct 2026 · pmt.sourceforge.io
Chunk handling
It can remove unwanted ancillary chunks or add chunks including gAMA, tRNS, iCCP, and textual chunks.Read 8 Oct 2026 · pmt.sourceforge.io
Compression modes
losslessRead 20 Sep 2026 · pmt.sourceforge.io
GUI options
The maker points to ImageOptim for Mac and Trimage for Linux, Windows, and Mac as free graphical applications that embed pngcrush with other image compressors or optimizers.Read 8 Oct 2026 · pmt.sourceforge.io
Image resizing
NoRead 20 Sep 2026 · pmt.sourceforge.io
Interface
pngcrush is a command-line application that runs from an MSDOS, UNIX, or Linux command line.Read 8 Oct 2026 · pmt.sourceforge.io
Latest version listed
The SourceForge files page lists pngcrush-1.8.11.tar.xz as the latest version.Read 8 Oct 2026 · sourceforge.net
Metadata controls
YesRead 20 Sep 2026 · pmt.sourceforge.io
Security note
The maker says the build linked statically with the supplied zlib is believed immune to the zlib-1.1.3 double-free bug because it detects and rejects double-free attempts.Read 8 Oct 2026 · pmt.sourceforge.io
Source and dependencies
The source is available from SourceForge and the pmt git repository, and the distribution includes libpng and zlib.Read 8 Oct 2026 · pmt.sourceforge.io
Supported formats
PNGRead 20 Sep 2026 · pmt.sourceforge.io
Windows binaries
The maker links to precompiled Windows binaries that run in an MSDOS window.Read 8 Oct 2026 · pmt.sourceforge.io

Plans and prices

pngcrush Free Open source; may be used, modified, and redistributed without a fee Read 8 Oct 2026 · pmt.sourceforge.io

Every pngcrush plan and price →

Strong points and limits

Strong points

  • Free to use, modify, and redistribute
  • Lossless PNG optimization
  • Supports batch processing
  • Can remove or add PNG chunks

Limits

  • Command-line interface
  • PNG only; no image resizing
  • No API access
  • Older unpatched libpng builds have overflow vulnerabilities

Who it suits

It suits users comfortable with command-line tools who need to optimize PNG files in batches or manage PNG chunks. The listed graphical alternatives may be relevant to users seeking a GUI.

Verdict

pngcrush is a focused option for lossless PNG optimization and chunk handling, with source and Windows binaries available. Users should note the command-line interface and the maker’s build-related security caveats.

Where Specifiction places it

Alternatives to pngcrushAll alternatives →