Implementation of the HTTP content negotiation algorithm

http://search.cpan.org/dist/HTTP-Negotiate/

Perl extensions for keeping data partially sorted

http://search.cpan.org/dist/Heap/

Lexically scoped subroutine wrappers for Perl

http://search.cpan.org/dist/Hook-LexWrap/

Various IO modules for Perl

http://search.cpan.org/dist/IO/

Perl5 compression modules (bzip2, deflate, gzip, zlib, zip)

http://search.cpan.org/dist/IO-Compress/

Perl module with object interface to AF_INET6 domain sockets

http://search.cpan.org/dist/IO-INET6/

IO::Multiplex - Manage IO on many file handles

http://search.cpan.org/dist/IO-Multiplex/

Perl5 interface to SSL sockets

http://search.cpan.org/dist/IO-Socket-SSL/

Simplified Perl5 module to handle I/O on in-core strings

http://search.cpan.org/dist/IO-String/

Flexible I/O Perl5 module that allows manipulation of pseudo-TTYs

http://search.cpan.org/dist/IO-Tty/

IO:: style interface to Compress::Zlib

http://search.cpan.org/dist/IO-Zlib/

Use IO handles with non-file objects

http://search.cpan.org/dist/IO-stringy/

Fast lookup of country codes from IP addresses

http://search.cpan.org/dist/IP-Country/

IPC::Run - Run subprocesses with piping and redirection

http://search.cpan.org/dist/IPC-Run/

A simple interface to access shared memory

http://search.cpan.org/dist/IPC-ShareLite/

IPC::Signal - Utility functions dealing with signals

http://search.cpan.org/dist/IPC-Signal/

Database connection caching and organization

http://search.cpan.org/dist/Ima-DBI/

Helper functions for PBM/PGM/PPM image file formats

http://search.cpan.org/dist/Image-PBMlib/

Perl5 module to determine the size of images in several common formats

https://metacpan.org/release/Image-Size

Perl extension to convert to JSON (JavaScript Object Notation)

http://search.cpan.org/dist/JSON/

Perl Wrapper Class for the various JSON classes

http://search.cpan.org/dist/JSON-Any/

JSON::XS compatible pure-Perl module

http://search.cpan.org/dist/JSON-PP/

Perl implementation of JSON-RPC 1.1 protocol

https://metacpan.org/release/JSON-RPC

JSON serialising/deserialising, done correctly and fast

http://search.cpan.org/dist/JSON-XS/

Perl extension to convert to JSON (JavaScript Object Notation)

http://search.cpan.org/dist/JSON/

Perl extension interface to convert Japanese text

http://search.cpan.org/dist/Jcode/

Guess media type for a file or a URL

http://search.cpan.org/dist/LWP-MediaTypes/

Perl extension for comparing lists

http://search.cpan.org/dist/List-Compare/

Provide the stuff missing in List::Util

http://search.cpan.org/dist/List-MoreUtils/

Perl extension to bring loggers and listeners together

http://search.cpan.org/dist/Log-Any/

Log4j implementation for Perl

http://log4perl.com

Perl5 module for Base32 encodings

http://search.cpan.org/dist/MIME-Base32/

Perl5 module for Base64 and Quoted-Printable encodings

http://search.cpan.org/dist/MIME-Base64/

Simple interface for creating (not parsing!) MIME messages

http://search.cpan.org/dist/MIME-Lite/

Set of perl5 modules for MIME

http://search.cpan.org/dist/MIME-tools/

Perl extension for determining MIME types

http://search.cpan.org/dist/MIME-Types/

Add mro::* interface compatibility for Perls < 5.9.5

http://search.cpan.org/dist/MRO-Compat/

Perl5 module to process and/or create DKIM email

http://jason.long.name/dkimproxy/

Perl implementation of DomainKeys

http://search.cpan.org/dist/Mail-DomainKeys/

Reference implementation of the RFC 4408 SPF protocol

http://search.cpan.org/dist/Mail-SPF/

Query Sender Permitted From for an IP,email,helo

http://spf.pobox.com

Perl module implementing a simple, platform-independent mailer

http://search.cpan.org/dist/Mail-Sendmail/

Perl5 modules for dealing with Internet e-mail messages

http://search.cpan.org/dist/MailTools/

Encoding and decoding of base36 strings

http://search.cpan.org/dist/Math-Base36/

Math::BigInt - Arbitrary size integer math package

http://search.cpan.org/dist/Math-BigInt/

Arbitrary big rational numbers

http://search.cpan.org/dist/Math-BigRat/

Perl extension for rounding numbers

http://search.cpan.org/dist/Math-Round/

Build and install Perl modules

http://search.cpan.org/dist/Module-Build/

Lets you find and use modules in categories

http://search.cpan.org/dist/Module-Find/

Loads one of several alternate underlying implementations for a module

http://search.cpan.org/dist/Module-Implementation/