ChatSecure is a free end-to-end encrypted messenger and phone calling app for smartphones. Users may exchange text, voice, video and other multimedia messages and securely call phone numbers worldwide. It allows users to send a WhatsApp-like interface of notifications to Android, Windows and iOS devices. Unlike WhatsApp, it uses an email/password to log in, allowing the user to send an encrypted copy of all chats and calls through a secure channel, and it doesn't require the phone number of a user to send or receive messages. The app also allows for file transfers to and from the device, similar to the ability of the file transfer service Skype. The app's development team states that it has a similar user experience and interface to the well-known encrypted instant messaging app Telegram.