unigram is very nice it is also as fast and secure as telegram but in unigram, I have found very nice UI and functionality. I love this application.
Trillian - Trillian is a decentralized and federated instant messaging platform that lets your whole company send private and group messages, keep tabs on what co-workers are doing, share files, and much more.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
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