Apps like Mattermost Classic

Here are some great alternatives to Mattermost Classic by Mattermost :
Output Messenger
Output Messenger
★3.4
Munin for Android
Munin for Android
★4.0
Simple HTTP Server
Simple HTTP Server
★4.2
Tusky for Mastodon
Tusky for Mastodon
★4.1
IMBox.me - Work messaging
IMBox.me - Work messaging
★3.7
CloudWeb - File & Web Server
CloudWeb - File & Web Server
★4.0
Wickr Enterprise
Wickr Enterprise
★3.7
Fedilab
Fedilab
★4.4
Nextcloud Talk
Nextcloud Talk
★4.0
Element - Secure Messenger
Element - Secure Messenger
★3.3
ArmorText
ArmorText
★4.4
CudaLaunch
CudaLaunch
★3.3
Pumble — Team Communication
Pumble — Team Communication
★4.3
Google Chat
Google Chat
★4.5
TeamSpeak 3 - Voice Chat
TeamSpeak 3 - Voice Chat
★3.2
Anonymous Messenger
Anonymous Messenger
★3.9