YMSG:
https://libyahoo2.sourceforge.net/
https://metacpan.org/pod/Net::YMSG
https://github.com/Richie-Zhang/Instant_Messenger/blob/master/documents/Yahoo%20Messenger%20Protocol
https://kb.imfreedom.org/protocols/yahoo/
https://github.com/chinpo-dev/ayyhoo
https://jymsg9.sourceforge.net/
https://gitlab.com/escargot-chat/server/-/wikis/YMSG-Protocol
http://web.archive.org/web/20100924153734/http://www.ycoderscookbook.com/tutorials/
https://github.com/afallenhope/web-ymsg
http://web.archive.org/web/20090623064155/carbonize.co.uk/ymsg16.html
http://web.archive.org/web/20040803082402/http://www.carbonize.co.uk:80/Tutorials/Vb/ycht.php
https://ninawiki.preloading.dev/wiki/Protocols/YMSG
https://ninawiki.preloading.dev/wiki/Protocols/YMSG/Packet_Structure
https://sourceforge.net/p/xmpppy/yahoo-transport/ci/master/tree/
YMSG8:
http://web.archive.org/web/20010801212305/http://www.venkydude.com:80/articles/yahoo.htm 1
YMSG9:
http://web.archive.org/web/20020806213426/http://www.venkydude.com:80/articles/yahoo.htm 2
YMSG10:
http://web.archive.org/web/20030811172816/http://venkydude.com:80/articles/yahoo.htm
YMSG11:
http://web.archive.org/web/20091229030156/http://www.venkydude.com/articles/yahoo.htm

MSNP (MSN and Skype MSNP24):
https://github.com/Richie-Zhang/Instant_Messenger/blob/master/documents/Internet%20Draft%20MSNP%201.0
https://ninawiki.preloading.dev/wiki/Protocols/MSNP/Documents
http://www.hypothetic.org/docs/msn/
https://protogined.wordpress.com/msnp2/
https://protogined.wordpress.com/msnp3/
https://protogined.wordpress.com/msnp4/
http://web.archive.org/web/20131225075151/http://msnpiki.msnfanatic.com/index.php/Main_Page
http://wiki.dequis.org/projects/msn/
https://github.com/kythyria/gallus/blob/master/doc/skypenotes.md
https://github.com/bitlbee/bitlbee/tree/wip/msnp24
https://github.com/uunicorn/pyskype
https://github.com/msndevs/skylogin
https://github.com/pangw/msnp-sharp.docs
http://imgate.wikidot.com/
https://www.codeproject.com/Articles/24444/Single-Sign-On-with-MSN-Protocol-15
http://www.mail-archive.com/amsn-devel@lists.sourceforge.net/msg04225/getclientconfig.log
https://github.com/v1ckxy/MSN
https://github.com/empereaux/msnp-server
https://www.process-one.net/blog/details_on_msns_xmpp_server/
https://github.com/chazizgrkb/heelercrap-node
https://github.com/chazizgrkb/heelercrap-csharp
https://code.google.com/archive/p/mzk/
https://web.archive.org/web/20091007102608/http://msnp-sharp.googlecode.com/svn/branches/MSNPSHARP_30_STABLE/WebServiceDefAndSchemas/
https://www.openrce.org/blog/view/449/MSNP15_authentication_scheme_REd
https://msnp.sourceforge.net/
https://web.archive.org/web/20110616062825/http://sourceforge.net/apps/trac/java-jml
http://web.archive.org/web/20090725053322/https://telepathy.freedesktop.org/wiki/Pymsn/MSNP/ContactListActions
http://web.archive.org/web/20090609100811/http://ml20rc.msnfanatic.com/vc_1_1/index.html
https://github.com/miranda-ng/miranda-ng/tree/v0.95.8/protocols/MSN
https://kb.imfreedom.org/protocols/MSN/
https://wenku.baidu.com/view/73b4f9fe941ea76e58fa0456.html
http://imgate.wikidot.com/

TOC:
http://web.archive.org/web/20070709075905/http://zimnox.com/?page=toc2
http://web.archive.org/web/20080920225323/https://terraim.svn.sourceforge.net/viewvc/terraim/trunk/terraim_source/src/toc/TOC2.txt
https://github.com/mlehman/Fluent.Toc
https://metacpan.org/dist/Net-AIM
https://web.archive.org/web/20090304025052/http://www.fluentconsulting.com/components/fluent.toc/
http://users.tmok.com/~smike/
https://tnt.sourceforge.net/
https://tik.sourceforge.net/
https://sourceforge.net/projects/phptoclib/
http://www.miniaim.net/
https://simpleaim.sourceforge.net/
http://web.archive.org/web/20120724222512/http://www.jamwt.com/Py-TOC/
http://web.archive.org/web/20061116183306/http://www.therisenrealm.com/scripts/bluetoc/
http://plaza.ufl.edu/dmitrid/perl/
https://github.com/wiseman/claim
https://metacpan.org/pod/Net::AOLIM
https://ninawiki.preloading.dev/wiki/Protocols/TOC/1.0

OSCAR:
https://web.archive.org/web/20060819080319/http://www.oilcan.org/oscar/
https://code.google.com/archive/p/joscar/wikis/FrontPage.wiki
https://ox.github.io/iserverd-oscar-mirror/
https://web.archive.org/web/20090420103942/http://dev.aol.com/aim/oscar
https://sourceforge.net/projects/pidgin/files/Pidgin/2.14.0/pidgin-2.14.0.tar.bz2/download
https://cdn.discordapp.com/attachments/1174055851103879211/1224416264676708462/snac_components.tcl
http://github.com/subpurple/aim-server
https://github.com/DrewML/aim-server
https://github.com/ox/aim-oscar-server
https://github.com/mk6i/retro-aim-server
https://github.com/Planet-Source-Code/brandon-scott-aol-instant-messenger-server-oscar__1-62118
https://www.kingant.net/oscar/
https://metacpan.org/dist/Net-OSCAR
http://web.archive.org/web/20051029182604/http://joust.kano.net/wiki/oscar/moin.cgi/
https://www.rejetto.com/wiki/index.php/ICQv7_protocol_resources
https://ninawiki.preloading.dev/wiki/Protocols/OSCAR/
https://ninawiki.preloading.dev/wiki/Protocols/WebAPI

MSIM:
http://myspaceim.pbworks.com/w/page/21992849/FrontPage
https://pastebin.com/wtKPmFir
http://web.archive.org/web/20071213062129/http://developer.pidgin.im/wiki/MsimProtocolSpec
https://kb.imfreedom.org/protocols/myspaceim/
https://sourceforge.net/p/xmpppy/myspace-transport/ci/master/tree/
http://wiki.jrudevels.org/MySpaceIM
https://gitlab.gnome.org/Archive/empathy/-/tags/EMPATHY_2_28_2

ICQ Mirabilis:
https://insecure.org/sploits/icq.spoof.overflow.seq.html
http://www.carfield.com.hk/document/networking/icq_protocol.html
http://web.archive.org/web/20050830013629/http://www.ihse.net/icq/
http://web.archive.org/web/20021014013528/http://www.algonet.se/~henisak/icq/icqv5.html
http://web.archive.org/web/20010215044710/http://omega.uta.edu/~tom/ICQ/
https://metacpan.org/pod/Net::ICQV5
http://www.micq.org/source/micq-cvs.tgz
https://neticq.sourceforge.net/
https://sourceforge.net/projects/neticq/files/OldFiles/
https://github.com/giuliano108/wireshark-rtpmon/blob/master/epan/dissectors/packet-icq.c
http://web.archive.org/web/19990209115631/http://www.student.nada.kth.se/%7Ed95-mih/icq/spec/v2/
http://web.archive.org/web/19990220052959/http://www.globalserve.net/%7Ejphowe/icq/
http://web.archive.org/web/19990209145716/http://www.student.nada.kth.se/%7Ed95-mih/icq/spec/v4/
http://web.archive.org/web/19991013131521/http://student.nada.kth.se/%7Ed95-mih/icq/spec/v5/v5-encryption.txt
https://github.com/miranda-ng/miranda-ng/tree/v0.95.11/protocols/ICQCorp

XFire:
https://github.com/darcymiranda/PFire
https://www.chrismoos.com/static/archive/research/Xfire/
https://kb.imfreedom.org/protocols/xfire/
http://web.archive.org/web/20150801123319/http://gfireproject.org/
https://github.com/gfireproject/gfire/tree/master
http://web.archive.org/web/20140105163440/http://xfirelib.sphene.net/wiki/show/XFireGateway.html/
http://web.archive.org/web/20140105163440/http://xfirelib.sphene.net/wiki/show/XFireGateway.html/

Skype P2P:
http://web.archive.org/web/20120328033542/http://skype-open-source.blogspot.com/2012/03/skype55-deobfuscated-released.html
http://www1.cs.columbia.edu/~salman/skype/index.html
https://en.wikipedia.org/wiki/Skype_protocol
https://kirils.org/skype/
http://www.oklabs.net/category/skype-reverse/
https://github.com/matthiasbock/OpenSkype
https://github.com/jeppeter/skype
http://web.archive.org/web/20100723101034/http://cryptolib.com/ciphers/skype/
http://web.archive.org/web/20160903213318/https://github.com/skypeopensource/skypeopensource2
http://www.oklabs.net/wp-content/uploads/2012/06/bh-eu-06-Biondi.pdf
http://www.oklabs.net/wp-content/uploads/2012/06/SSTIC06-Desclaux-Castle_in_the_Skype.pdf
http://www.oklabs.net/wp-content/uploads/2012/06/vskype-part1.pdf
http://www.oklabs.net/wp-content/uploads/2012/06/vskype-part2.pdf
https://sourceforge.net/p/xmpppy/skype-transport/ci/master/tree/
https://files.epicness.wtf/Skype/

OCS/Lync/Skype for Business:
https://sipe.sourceforge.io/

Mail.ru Agent:
http://wiki.jrudevels.org/Mail.Ru_Agent_client
http://wiki.jrudevels.org/Mail.Ru_Agent
https://web.archive.org/web/20080206205801/https://agent.mail.ru/protocol.html

MSN Explorer:
https://wink.messengergeek.com/t/msn-explorer/8948
https://github.com/Sgeo/MSN-Explorer-Enabler

Napster:
https://opennap.sourceforge.net/

MSN Chat:
https://ziggythehamster.sh/downloads/msnocx/
https://ziggythehamster.sh/downloads/activex/