- aftpd - aftpd is an FTP server written in Common Lisp
- Allegro NFS Server - Allegro NFS Server for Microsoft Windows, written in Common Lisp
- carrier - Carrier is an async HTTP client driven by cl-async and fast-http
- chaos-lisp - chaos-lisp implements a multi-threaded ChaosNET Network Control Program under OpenMCL running on Mac OS X, interfacing with Unix-domain sockets containing emulated ChaosNET packets
- Chunga - Chunga is a web/networking library which implements portable chunked HTTP streams as described in RFC 2616
- CL+SSL - CL+SSL is a portable interface to OpenSSL
- cl-agraph - CL-AGRAPH is a minimal portable Lisp client for AllegroGraph
- cl-async - Cl-async is a asynchronous I/O library wrapping the libuv C library
- cl-cidr-notation - cl-cidr-notation is a library for converting IP addresses and CIDR blocks from integer to string representations and vice versa
- cl-curl - Cl-curl is a set of Lisp binding to the C libcurl HTTP client library, a multiprotocol file transfer library
- CL-DBUS - CL-DBUS aims to be an implementation of the popular D-BUS IPC/networking protocol
- CL-DTYPE - CL-DTYPE is a Common Lisp library implementing the DType networking protocol, introduced by MIT Media Labs
- cl-fix - cl-fix enables you to write FIX-based systems using Common Lisp
- cl-flowd - cl-flowd is an native Common Lisp interface to the flowd Netflow collector
- CL-FTP - cl-ftp is an FTP client
- cl-growl - Growl is a notification system for Mac OS X
- CL-MEMCACHED - CL-MEMCACHED is a fast interface to the memcached object caching system
- cl-net-snmp - cl-net-snmp is an SNMP library for Common Lisp
- cl-oauth - cl-oauth is an implementation of the OAuth<a> 1.0a API authorization protocol
- cl-openid - Cl-OpenID is an implementation of OpenID protocol in Common Lisp
- CL-PLUS-SSL - This library is a fork of SSL-CMUCL
- cl-sasl - cl-sasl is a client implementation of the Simple Authentication and Security Layer (SASL) networking protocol
- CL-TELNETD - CL-TELNETD is a CL telnet networking server
- CL-TLS - CL-TLS is a prototype Common Lisp implementation of TLS and related protocols and standards including:
- CL-ZEROCONF - CL-ZEROCONF is a networking library for Lisp that handles Zeroconf service discovery (popularized by Apple's implementation, originally called Rendezvous and renamed to Bonjour for OS X 10.4)
- CLERIC - CLERIC (Common Lisp Erlang Interface) is an implementation of the Erlang distribution protocol, comparable with erl_interface and jinterface
- CLOCC - The Common Lisp Open Code Collection contains Lisp code for various
- CLX - CLX provides an implementation of the X Window System protocol to Lisp graphics library[ies] and applications
- CLXS - CLXS is an early-stage implementation of an X11 server (the part that does the drawing and keyboard/mouse handling) in Common Lisp
- Etiquette - Etiquette is a networking protocol construction framework
- find-port - Find open ports programmatically
- IOlib - I/O(mainly networking) library containing: a BSD sockets library, a DNS resolver and an I/O multiplexer that supports select(2), epoll(4) and kqueue(2)
- ip - A library to work with IPv4 addresses
- ip-interfaces - ip-interfaces provides a convenient way to obtain a list of available networking interfaces on a machine
- ipcalc - A Common Lisp library for manipulating and calculating IPv4 and IPv6 network addresses
- jarw-inet - jarw-inet supports several Internet networking Standards including writing servers and clients, http, smtp, nntp protocols, header parsing, mime decoding
- LENS - Lisp Educational Network Simulator (LENS) provides a Common Lisp environment for network simulations
- LispWorks-UDP - UDP networking for LispWorks
- NET.QUADIUM.LDAP - NET QUADIUM LDAP is an LDAP library for Common Lisp
- NET.QUADIUM.LDIF - NET QUADIUM LDIF is an LDIF (LDAP Data Interchange Format) library for Common Lisp
- NET4CL - NET4CL is a collection of network functions, mostly encapsulation of existing functions to uniform the interface between different Lisp systems
- org-davep-dict - org-davep-dict is a Common Lisp networking protocol library for talking to a dict server
- OSC - An implementation of the OpenSoundControl protocol
- plokami - PLOKAMI is a libpcap/winpcap interface
- Saluto - Saluto is a submodule for RESTAS web-framework, which allow web-site users to be authorized with OAuth 2.0 protocol
- Slitch - A not-very-under-development-lately-but-will-get-back-to-it-some-day-soon TCP/IP networking stack in CMU Common Lisp (CMUCL)
- SSL-CMUCL - SSL-CMUCL is an interface to SSL streams for CMUCL
- teepeedee2 - teepeedee2 is a fast HTTP server and web framework
- telnetlib - telnetlib is a networking library for doing Telnet
- trivial-ldap - TRIVIAL-LDAP is a one-file, pure-Lisp client library for parts of RFC 4510 - Lightweight Directory Access Protocol (v3), LDAP
- trivial-sockets - trivial-sockets is a trivial networking library for undemanding Internet applications (for example "scripting" and interactive use)
- unicly - UUIDs (Universally Unique Identifiers) v1-v5 per RFC 4122
- usocket - USOCKET is a networking portability layer for BSD-style sockets
- Usocket-UDP - UDP networking patch for USOCKET
- uuid - A library for generation of universally unique identifiers (UUIDs) as described by RFC 4122
- Volemad - VOLEMAD is an application for quickly interacting with Mullvad’s WireGuard servers, written in Common Lisp
- Woo - Woo is a fast async HTTP server built on top of libev, with aim to be the fastest
- zen - zen is a hackable X server written in Common Lisp
Dealing with email: (main topic: email)
- Allegro Maild - Allegro Maild is an SMTP email server written in Common Lisp
- cl-icalendar - An implementation of the iCalendar (RFC 5545) file format
- CL-MIME - CL-MIME is a library for constructing and manipulating MIME objects in Common Lisp
- cl-pop - CL-POP is a lisp networking library that provides a POP email client based on RFC 1939
- CL-Sendmail - CL-Sendmail is a library for sending email using the external program 'sendmail'
- CL-SES4 - AWS SES email sender using Signature Version 4 of Amazon's API
- CL-SMTP - CL-SMTP is an SMTP (RFC 5321) client
- clonsigna - Clonsigna is a Common Lisp library that allows interaction with IMAP4rev1 servers
- CLPMR - CLPMR is the Common Lisp ProcMail Replacement
- cocoa-mail - cocoa-mail is a basic interface for OpenMCL on Mac OS X to the Cocoa Mail infrastructure
- de.setf.utility - de setf utility is a collection of Common Lisp utilities functions and several purpose-specific libraries
- Demyltify - Demyltify is a library that lets you write Sendmail email filters (milters) in Common Lisp
- esmtp-client - esmtp-client is a library for sending email via SMTP according to RFC 6409
- imap - imap is a client library for Allegro CL for sending and receiving email with support for POP, IMAP and SMTP
- jarw-inet - jarw-inet supports several Internet networking Standards including writing servers and clients, http, smtp, nntp protocols, header parsing, mime decoding
- macho - Macho is an email web archiving system, similar in scope to pipermail or mhonarc
- MARCH - MArch is a daemon program that saves email going through a mail server into a database
- mel-base - mel-base is a library for handling email with support for Maildir, POP3, IMAP and SMTP folders
- org-davep-newsrc - org-davep-newsrc is a Common Lisp library that provides a couple of classes for reading a Unix Usenet newsrc file
- org-davep-nntp - org-davep-nntp is a Common Lisp library for talking to an NNTP (RFC 3977) server
- rfc2822 - Text email as defined in RFC 2822
- smta - smta is a simple SMTP email server
- smtp4cl - SMTP4CL is a SMTP client library to send messages to an MTA (Mail Transport Agent)
- trivial-email-utf-8 - trivial-email-utf-8 is like CL-SMTP's send-mail, but qprints any Unicode characters in the message title or content and includes the appropriate headers if necessary
Libraries specific to MIME: (main topic: MIME)
- CL-MIME - CL-MIME is a library for constructing and manipulating MIME objects in Common Lisp
- cl-qprint - cl-qprint is a library for encoding to and decoding the quoted-printable (MIME) data format
- CL-RFC2047 - CL-RFC2047 impements the encoding described by RFC 2047 (MIME)
- CLPMR - CLPMR is the Common Lisp ProcMail Replacement
- media-types - Query and compare media types
- MIME4CL - MIME4CL allows you to craft MIME compliant messages or to parse and handle them programmatically
Dealing with URIs: (main topic: URI)
- cl-base64 - cl-base64 provides base64 (RFC 1521) encoding and decoding
- cl-routes - cl-routes is Common Lisp re-implementation of the Rails routes system for mapping URL's (also, see https://routes.readthedocs.io/en/latest/)
- cl-slug - cl-slug is a small library to make slugs, mainly for URIs, from english and beyond
- cl-tld - Extract eTLDs based on the Public Suffix List, e.g
- cl-uri-templates - cl-uri-templates is an implementation of URI-Templates that supports the full draft 03 URI Template standard
- CLLIB - CLLIB is a varied collection of Common lisp tools and routines in CLOCC
- froute - froute is a routing library taking advantage of the MOP
- http-routes - http-routes is a library which attempts to create capable http(url) routes lib without regexps
- idna - International Domain Name functions for Common Lisp
- machina-policy - machina-policy is a way to parse and query robots.txt files so your web-scraping bot can be a good bot instead of a bad bot
- PERCENT-ENCODING - PERCENT-ENCODING is a library for URI percent encoding/decoding as specified in RFC3986
- puri - puri, Portable Universal Resource Identifier, is a library for parsing and representing URIs
- PURL - PURL provides a parser and defines a type for URLs as specified in RFC1738
- quri - quri (pronounced "Q-ree") is yet another URI library for Common Lisp
- simple-routes - Simple-routes adds quick and easy, centralized http routing to Hunchentoot
- Snooze - Snooze is an URL router for Common Lisp designed around REST web services
- uri-template - uri-template is an implementation of the URI Template proposed standard draft version 01 as a
- Ystok-URI - Ystok-URI a library for representing, parsing, and printing URIs
Messaging: (main topic: messaging)
- Cl-BUNNY - RabbitMQ Client - CL-BUNNY is a RabbitMQ client
- CL-HRAC - RabbitMQ Management HTTP API in Common Lisp
- cl-stomp - cl-stomp is an implementation of STOMP (Streaming Text Orientated Messaging Protocol)
- cl-xmpp - cl-xmpp is an XMPP client implementation of RFCs 3920 and 3921 which can be thought of as the basis of any Jabber-compliant client
- cl-zmq - cl-zmq is a set of CFFI bindings for ZeroMQ messaging system
- CLAIM - CLAIM is an implementation of AOL's semi-open Instant Messaging protocol, TOC (see PROTOCOL.txt)
- Climc - A Common Lisp Instant Messaging Client
- de.setf.amqp - de setf amqp is a native Common Lisp Advanced Message Queuing Protocol client
- erlangen - erlangen is a distributed, asynchronous message passing system for Clozure Common Lisp
- glacier - Lightweight wrapper for making Mastodon bots
- NactivityPub - ActivityPub & ActivityStreams support library for Common Lisp
- pzmq - ZeroMQ 4.0+ CFFI bindings
- tinmop - TUI/GUI client application for Gemini, Gopher, kamid, and Mastodon/Pleroma
Wire formats: (main topic: wire format)
- ASN.1 - Abstract Syntax Notation #1, the Common Lisp implementation and language mapping
- cl-frugal-uuid - Common Lisp UUID library with zero dependencies
- cl-marshal - Simple and fast marshalling of all kinds of Lisp data structures
- cl-protobufs - CL-PROTOBUFS is a library to use Google Protocol Buffers in Common Lisp, originally written by Scott McKay at ITA by Google
- cl-stomp - cl-stomp is an implementation of STOMP (Streaming Text Orientated Messaging Protocol)
- dbus - A D-Bus client library for Common Lisp
- de.setf.thrift - de.setf.thrift is a binding for the Apache Thrift framework for scalable cross-language services development
- drx - An eXtensible Data Representation (XDR) implementation in Common Lisp
- jzon - A correct and safe(er) JSON RFC 8259 reader/writer with sane defaults
- S-PROTOBUF - S-PROTOBUF is a library to encode data in the Google Protocol Buffers wire format
- Swank - Swank is distributed as part of SLIME
- userial - A Common Lisp library for serializing to binary buffers
IRC clients and bots: (main topic: IRC)
- beirc - beirc is a CLIM IRC client application using the cl-irc library as a backend, initially written by Gilbert Baumann, now maintained by Dave Murray and others
- Birch - Birch is a simple IRC client library
- cl-irc - cl-irc is an IRC library written in Common Lisp
- Colleen - Colleen is yet another IRC chat bot framework
- girc - gIRC is a basic IRC client application for the terminal
- IRC Quotes - Some moments from IRC, preserved for posterity, some humorous
- irc-logger - irc-logger is a networking library written by Kevin Rosenberg which uses the cl-irc library to provide multichannel Internet Relay Chat (IRC) logging
- Lisp IRC Bots - There are several IRC bots written in Lisp
- lispcafe - #lispcafe on www.libera.chat
- lisppaste - lisppaste sits on a webserver and users can paste text into it
- Maiden - Maiden is a collection of systems to help you build applications and libraries that interact with chat servers
- minion - minion is an IRC robot (who prefers the term "electronically composed.") For online help, try /msg minion help
- orcabot - A full-featured IRC bot in Common Lisp
- trivial-irc - trivial-irc is a small IRC library that provides only very basic facilities for communicating with IRC servers, and has no facilities for extensions like DCC, CTCP etc
- WeirdIRC - WeirdIRC is a simple IRC client using CLIM
- X-Chat Common Lisp Plugin - The X-Chat Common Lisp plugin is a plugin for X-Chat version 2 and up (the famous IRC client) that allows you to use Common Lisp scripts to control X-Chat behaviour