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Signal is a cross-platform encrypted messaging application that has a strong focus on privacy. The application is developed by Signal Messenger LLC and provides users with features like one-to-one and group messages, which can include files, voice notes, images and videos. The software is famous for being used by the whistleblower and privacy advocate Edward Snowden who once said "I use Signal every day, it is the most scalable encryption tool we have".

Element is an All-in-one secure chat app for teams, friends and organisations that allow you to own your conversations. With Element you can keep conversations in your control, safe from data-mining and ads. Element utilize the open and global Matrix network for message relay, protected by proven end-to-end encryption.

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Slack is a new way to communicate with your team in a faster, better organized, and more secure than email. The software is designed for business looking to improve their communication work flow. Slack offers features like persistent chat rooms organized by topic, private groups, and direct messaging that is built for teamwork.

Zulip is an open-source real-time chat with an email threading model. With Zulip, you can catch up on important conversations while ignoring irrelevant ones. Zulip provides modern apps for every major platform, powered by Electron and React Native. The software is 100% open source software, built by a vibrant community of hundreds of developers from all around the world.

Skype is a telecommunications application that specialize in providing video chat and voice calls between computers, tablets, mobile devices and consoles. The software allows you to connect with friends and business colleges worldwide. Skype provides free online calls, messaging, affordable international calling to mobiles or landlines and Skype for Business for effective collaboration among teams.