Services

Chat

• IRC (see also, Suika, ZNC)
• XMPP

Communications

• Mail

File sharing

• Marisa

Forums

• Citadel
• NNTP
• PhpBB
• Postmill

Frontends

• Keine
• Mai
• Yukari

Pubnix

• Geidontei

Social media

• Misskey

Version control

• CVS
• Git
• Mercurial
• Subversion