Alternatives to LekkerIM for all platforms with any license

Skype

An instant messaging app that provides online text message and video chat services.

Freemium Mac Windows Linux Web Android ... iPhone Blackberry Chrome OS Windows S Android Tablet BSD Windows Phone iPad Apple Watch Android Wear PortableApps.com
Share your screen Video calling Video calling Exchange Integration ... Group Messaging IFTTT integration Microsoft Office integration Video calling Voice Call Add a feature

2414 Like
Slack

Slack brings all your communication together in one place. It's real-time messaging, archiving and search for modern teams.

Freemium Mac Windows Linux Web Android ... iPhone Chrome OS Windows S BSD Electron / Atom Shell Software as a Service (SaaS)
Group chat Group collaboration Multi Channel Team Collaboration ... Extensible by Plugins/Extensions App integration Channel manager Direct file uploading IFTTT integration Integrated File Sharing Live Push Notifications Support for @mentions Multiple channels Multiple teams Onboarding Out Of The Box Reactions Real time collaboration Team work Video calling Voice Call Add a feature

660 Like
Mattermost

Mattermost is an open source, self-hosted Slack alternative. As an alternative to proprietary SaaS messaging, Mattermost brings...

Freemium $ $ $ Open Source Mac Windows Linux Android iPhone ... Android Tablet iPad Self-Hosted JavaScript Go (Programming Language) Cloudron
Team Collaboration Group chat Data API Integrated File Sharing ... MarkDown support On-premises software Plugin API File Sending Slack integration Supports XMPP Add a feature

152 Like
Matrix.org

Matrix is an open standard for decentralized persistent communication over IP. It can be used for decentralised group chat, WebRTC signaling, IoT-data transfer, ...

Free Open Source Mac Windows Linux Web Android ... iPhone Android Tablet iPad Self-Hosted WebRTC Python JavaScript Go (Programming Language) Java Perl
Apps with End-to-End Encryption Decentralized Chat Bot Distributed ... Encrypted chat GNU/linux-libre Group chat Real time collaboration Server side history Team Collaboration Voice Call WebRTC Add a feature

113 Like
Rocket.Chat

Rocket.Chat is a Web Chat Server, developed in JavaScript, using the Meteor fullstack framework.

Free Open Source Mac Windows Linux Android iPhone ... Self-Hosted Cloudron
Group chat Ad-free Chat Bot Extensible by Plugins/Extensions ... Integrated File Sharing Location Mapping Share your screen Self-Serve Capability Slack integration Voice messages Add a feature

84 Like
Glip

Glip is instant messaging for teams and businesses to communicate and get work done at the same time. In Glip you work where your conversations are, so you always know...

Freemium Mac Windows Web Android iPhone ... Android Tablet iPad
Social feed Bitbucket Integration Box.com integration Built-in File Manager ... Calendar view CRM Dropbox integration GitHub integration Google Drive integration Group chat Group collaboration Integrated Chat Mailchimp integration Meeting notes Onedrive integration Real time collaboration Recurring tasks Share your screen Shared calendars Software as a Service Calendar Sync Team Collaboration Team work Trello integration Zapier integration Zendesk integration Add a feature

155 Like
HipChat

HipChat is an instant messaging service designed for companies and teams. It has persistent chat rooms, one-to-one chat, searchable chat history, file sharing via drag...
- Discontinued https://alternativeto.net/software/slack/ is acquiring Hipchat and https://alternativeto.net/software/stride-by-atlassian/ from Atlassian. the services will be discontinued after February 15th, 2019. https://www.atlassian.com/partnerships/slack
Freemium Mac Windows Linux Web Android ... iPhone Android Tablet iPad Self-Hosted Apple Watch
Team Collaboration Integrated File Sharing Share your screen Add a feature

73 Like
Let's Chat

Self-hosted chat for small teams. Features and Stuff BYOS (bring your own server) Persistent messages Multiple rooms New message alerts /...
- Discontinued As stated at https://github.com/sdelements/lets-chat/issues/781 , the project is no longer developed since August 2017. Last version, 0.4.0, released in June 2015, can be still downloaded from GitHub together with the source code.
Free Open Source Self-Hosted Cloudron
Team Collaboration Add a feature

36 Like
YakYak

What does it do: * Send/receive chat messages * Create/change conversations (rename, add people) * Leave/delete conversation * Notifications * ...

Free Open Source Mac Windows Linux Hangouts
Portable Add a feature

18 Like
ZeroChat

An IRC-like internet chatroom hosted on ZeroNet, a distributed network. 0rc is a fully distributed website, and messages are shared through peers using the ZeroNet...

Free Open Source Mac Windows Linux Web Self-Hosted ... Python JavaScript ZeroNet
Decentralized Distributed Add a feature

10 Like
Dialog Messenger

Dialog Messenger is a customized self-hosted platform usable across multi operation systems simultaneously. dialog provides SDK tools for client interface as well as for...

Free Personal Mac Windows Linux Web Android ... iPhone Self-Hosted
Encrypted chat Reactions Real time collaboration Team work ... Text chat Add a feature

24 Like
Ripcord

Ripcord is a desktop chat client for group-centric services like Slack and Discord. It provides a traditional compact desktop interface designed for power users....

Free Mac Windows Linux Discord Slack
Slack client Slack integration Add a feature

6 Like
Spectrum Chat

A newly open sourced self hosted Slack like alternative for building persistent chat communities.

Freemium $ $ $ Open Source Web Self-Hosted
Group chat Group collaboration Support for @mentions Real time collaboration ... Team Collaboration Team work Add a feature

6 Like
VideoMeeting

VideoMeeting is a free and open source video conference solution built to have video calls and chats using your web browser. It is a pure web application based on WebRTC...

Free Open Source Web Chrome OS Self-Hosted
Video calling Web-Based Add a feature

4 Like
TribeScale

TribeScale is a startup that aims to enhance teamwork in companies through the improvement of communication, coordination, and the pace on the basis of targets set.
- Discontinued Website and app unavailable.
Free Mac Windows Web Android iPhone ... iPad Self-Hosted
Goal setting Goal Tracking Group chat Group collaboration ... Real time collaboration Team Collaboration Team work Add a feature

24 Like