Telegram is a free instant messaging app which works on all your devices: Android, iOS, PC, Mac, Linux, Windows Phone, and there's a web version to cover everything else.
You can have the app running simultaneously, everywhere, if you like-- Telegram automatically keeps everything in sync.
Chats can be simple, just you and one or two friends. Add some stickers, use the animated GIF search, or share some pictures of your own. There's even a capable photo editor to make sure your images are looking their best.
But that's just the start. You could also work with groups of up to 5,000 people, and share an unlimited number of photos, videos, archives, or any other file type up to a maximum of 1.5 GB each. And if there's not enough space on your device, no problem-- keep it in the cloud. (It's still free.)
Powerful privacy features include "Secret Chats", a special type of encrypted message which can be set to self-destruct in a set time after it's been read.
An open API enables developers to extend the app with smart bots and custom Telegram clients.
And all this is based on a network of servers distributed around the world, delivering excellent performance wherever you are.
Note this is the portable version of Telegram.