I consider info-zip, not PKZIP, the de facto standard implementation for ZIP files. It's free software and it is available on VMS, MS-DOS, and uncountable[0] other platforms, and it has been implementing extensions like 64-bit support, bzip2 compression and more.

But it seems info-zip.org has expired and is controlled by a domain squatter.

The latest versions released were Zip 3.0 in 2008 and Unzip 6.0 in 2009.

Is it perfected? OOXML 2016 and OD v1.2 from 2015 define PKZIP 6.2.0 from 2004 as their ZIP, but the latest ISO/IEC 21320-1:2015 ZIP standard uses the 2012 PKZIP 6.3.3 definition.

Steven Schweda [1] posted a comment to the SourceForge tracker just a few months ago, so it seems the project is alive in some capacity. 3.1 and 6.1 betas were mentioned in their forums in 2015.

[0] Hyperbole. Just go to the release notes and count them: http://infozip.sourceforge.net/UnZip.html

[1] https://sourceforge.net/u/antinode2/profile/