Telegram is a messaging app created by former VK creators with a focus on speed and security. It’s superfast, simple and free. It is like SMS, but more powerful.
You can send messages, photos and videos to people who are in your phone contacts (and have Telegram). You can also create groups for up to 20000 people or channels for unlimited subscribers.
For those interested in maximum privacy, Telegram added Secret Chats, featuring end-to-end encryption to ensure that a message can only be read by its intended recipient. More Info »
Telegram's client-side code is open-source software, whereas its server-side code is closed-source and proprietary. The service also provides public APIs with which developers can access the same functionality as Telegram's official apps to build their own messaging applications.