Base class SAX Drivers and Filters

https://metacpan.org/release/XML-SAX-Base

Simple API for XML

https://metacpan.org/release/XML-SAX-Expat

SAX2 XML Writer

https://metacpan.org/release/XML-SAX-Writer

Trivial API for reading and writing XML (esp config files)

https://www.mclean.net.nz/

XML::Stream provides you with access to XML Stream

https://metacpan.org/release/XML-Stream

Pure Perl implementation for parsing/writing xml files

https://metacpan.org/release/XML-TreePP

Process huge XML documents by chunks via a tree interface

https://metacpan.org/release/XML-Twig

Simple Perl module for writing XML documents

https://metacpan.org/release/XML-Writer

Modules for parsing and evaluating XPath statements

https://metacpan.org/release/XML-XPath

YAML implementation in Perl

https://metacpan.org/release/YAML

Read/Write YAML files with as little code as possible

https://metacpan.org/release/YAML-Tiny

Disables bareword filehandles

https://metacpan.org/release/bareword-filehandles

Transparent BigNumber/BigRational support for Perl

https://metacpan.org/release/bignum

Perl common defaults with lower memory usage

https://metacpan.org/release/common-sense

Perl Modules of ePerl package: Parse::ePerl, Apache::ePerl

http://www.ossp.org/pkg/tool/eperl/

Lexically warn about using the indirect object syntax

https://metacpan.org/release/indirect

Perl5 library for WWW access

https://metacpan.org/release/libwww-perl

Collection of Perl5 modules for working with XML

https://metacpan.org/release/libxml-perl

Disables multidimensional array emulation

https://metacpan.org/release/multidimensional

Keep imports and functions out of your namespace

https://metacpan.org/release/namespace-clean

Establish an ISA relationship with base classes at compile time

https://metacpan.org/release/parent

Client interface to LDAP (includes Net::LDAP)

https://metacpan.org/release/perl-ldap

Turn on strict and make all warnings fatal

https://metacpan.org/release/strictures

Perl bindings for Version control system

http://subversion.apache.org/

Perl interpreter-based threads

https://metacpan.org/release/threads

Perl extension for sharing data structures between threads

http://search.cpan.org/dist/threads-shared/

Script that helps install Postscript fonts in X Window System

Perl extension for Version Objects

https://metacpan.org/release/version

File archiver with high compression ratio

http://p7zip.sourceforge.net/

Generic visualization tool for GNUstep (Gantt chart and more)

http://www-id.imag.fr/Logiciels/paje/

Authenticate applications requiring PAM services

http://www.marcuscom.com/pam_helper/

Pam module for authenticating with LDAP

http://www.padl.com/OSS/pam_ldap.html

Open-source framework for the layout and rendering of i18n text

https://www.pango.org/

C++ wrapper for Pango

http://gtkmm.sourceforge.net/

Deprecated pangoX support

http://www.pango.org/

Mail/MIME handling library for GNUstep

https://www.nongnu.org/gnustep-nonfsf/gnumail/index.html

GNU patch utility

https://savannah.gnu.org/projects/patch/

Small collection of programs that operate on patch files

http://cyberelk.net/tim/software/patchutils/

Measurement tool for capacity estimation of network paths

http://www.pathrate.org

PC-BSD registry editor

http://www.pcbsd.org/

Parallel BZIP2

http://compression.ca/pbzip2/

The Portable C Compiler

http://pcc.ludd.ltu.se/

Purdue Compiler Construction Tool Set

http://www.polhode.com/pccts.html

Database of all known IDs used in PCI devices

https://pci-ids.ucw.cz/ https://github.com/pciutils/pciids

Perl Compatible Regular Expressions library

https://www.pcre.org/

Middleware library to access a smart card using SCard API (PC/SC)

https://pcsclite.apdu.fr/

C library for dynamically generating PDF

http://www.pdflib.de/

The Public Domain Korn Shell

http://www.cs.mun.ca/~michael/pdksh/

Caching (permanently, writes to disk on exit) DNS proxy-server

http://members.home.nl/p.a.rombouts/pdnsd/

PEAR framework for PHP

https://pear.php.net/