Dialog Messenger - handy and feature-rich enterprise multi-device messenger available for server or cloud – Slack-like, but not Slack-limited

LAN Messenger - LAN Messenger is a decentralized UDP IM-style chat client which supports usernames...

Ripcord - A desktop chat client for Discord and Slack

Feem - Share files offline. No servers. No cloud. No limits.

Done Hui - No need to switch between multiple pieces of software to get through the workday. CHATS: Communicate freely. CALENDAR: Know your team's availability, plan meetings. No more conflicts. TO-DOs: Stay on top of all projects. FILES: All files, one spot.

BeeBEEP - You can message and share files inside your intranet without a server.