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.
Webogram - Webogram is an unofficial Telegram web app.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Telegram X - Meet Telegram X for iOS and Android – two new official apps that offer more speed, longer batter life and smooth animations.
Plus Messenger - Free Android Messenger that uses Telegrams API.
tg - Command-line interface for http://alternativeto.net/software/telegram/. Uses readline interface.
Vidogram - Vidogram is a fast and secure messenger based on Telegram with a lot of additional Features