PNG Reference Library: libpng

PNG Web Site


This is an open source project to develop and maintain the reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files.

UPDATE 29 September 2017:

  • The latest released versions are
    • libpng-1.5.30 and
    • libpng-1.6.34

    [DOWNLOAD from SourceForge or from OSUOSL]

  • For legacy applications,
    • libpng-1.4.22,
    • libpng-1.2.59, and
    • libpng-1.0.69
    are also available and will only be updated if necessary for security reasons.

UPDATE 28 September 2017: The latest development version is

  • libpng-1.7.0beta89.

[DOWNLOAD from SourceForge or from OSUOSL]

libpng17 has 8-bit compose and rgb_to_grayscale accuracy improvements, improved filter selection and compression strategies, and a new "affirm" (similar to "assert()") bug reporting system.

The primary web site for PNG is

The primary public ftp site for libpng is
This site will also respond to https and http requests:
Thanks to the Oregon State University Open Source Laboratory.

The previous ftp site is still being maintained at, but the OSUOSL site is much faster and has a more complete archive of old versions.

The ftp site for beta versions of libpng is also at

The current public and beta versions of libpng are also available at

There are pointers to various distributions of libpng and MD5 checksums here.

You can receive notifications of libpng releases through, at

The Sourceforge project page for libpng is at

A "git" repository for libpng is available. You can access it by cloning git:// or you can browse it at or at At present, there are eight branches:

  • libpng00,
  • libpng10,
  • libpng12,
  • libpng14,
  • libpng15,
  • libpng16,
  • libpng17, and
  • master

The "master" branch is roughly equivalent to the "libpng16" branch. Development occurs in the "libpng16" and "libpng17" branches; parts of the new developments are also ported to the "libpng15" branch; the rest are just for legacy and security purposes.

A "doxygen" index for various releases is available at

An "ABI compatibility analysis" of libpng releases is available at abi-laboratory

The Coverity project for libpng is at The project is set up to scan the head of each of the libpng10 through libpng17 branches (libpng00 is not included). As of December 3, 2015, libpng-1.0.65, libpng-1.2.55, libpng-1.4.18, libpng-1.5.25, libpng-1.6.20, and libpng-1.7.0beta70 were all reported to be defect-free).

The mailing list for libpng developers and developers of libpng-based applications is png-mng-implement (at) Visit to subscribe. (archived here)

Bug reports can be sent to the mailing list or submitted via the SourceForge Bug tracker (select the "Create Ticket" button) or as an issue at github.

If you wish to privately report a security issue (vulnerability) in libpng, please report it by email to png-mng-security at, where it will be seen by a small group of long-time libpng contributors. You don't need to subscribe (in fact you probably won't be allowed to subscribe) to that list. If all else fails, you may send email to glennrp at gmail dot com or to glennrp at comcast dot net.

Feel free to download and use the official PNG logo (size 88x31) with your application documentation and web pages:

pngbar.png pngbar.png pngbar.jpg pngbar.jpg
Both pngbar.tar.gz Both
This site belongs to the PNG Development Group and is maintained for the group by Glenn Randers-Pehrson glennrp at

Web space for this project is being provided by