Viber is a cross-platform instant messaging app used on smartphone. It works along with 3G and WIFI networks. Viber first launched on the iPhone; and Android test version came out in May 2011, and then the official launch was on July 20.

Skype is a free instant messaging application that makes the communication more convenient and interesting. It supports video chat, voice meeting, text chat, file transfer, and other communication functions, which greatly satisfy users' different needs and using habits.

Snapchat is a photo sharing application developed by two students from Stanford University.

TextNow is an application used for sending messages. This application is available on Android, iOS and Windows Phone systems.

Kik is an online social application where users can post photos, videos and others to interact with their friends.

Text Free is free for texting and calling with a real US phone number. You can send text to anyone, even though they don't have the app. Enjoy free SMS messaging, group messaging, calling and voicemail with Text Free! You can send unlimited free texts and free MMS picture messages to all your friends, even if they don’t have Textfree app!

Line is a popular online messaging application that is developed by NHN Japan. The most attractive part to users is “emotion images”. There are more than 250 kinds of emotion images for users to enjoy using Line. Line is a brand new communication tool for users to have free calls, free texts within 24 hours at any time anywhere.

KakaoTalk is an online messaging application which supports the functions of sending messages, images, voice and videos for free.

Talkatone is a communication app developed by Talkatone, Llc, which allows users to make free phone calls or text via the Internet connection. Keep in touch with your family and friends by calling and texting whenever and wherever you like with Talkatone.

Developed by textPlus, Nextplus is a communication application where users can enjoy the phone calls, text, messages across the US, Canada for free. It also allows users to send and receive an unlimited amount of text messages. Nextplus offers people comprehensive phone service all in one app, and there are no contracts, phone purchase, commitments or hidden fees.

Initially released on BlackBerry 1 July 2009, Truecaller developed by True Software Scandinavia AB is an app where you can have safe and efficient communication. It enables users to search for the contact details with the given name or telephone number. Besides, it features users to update the contacts' pictures and birthdays of the phonebook. Truecaller is available for multiple devices, such as Android, iOS, BlackBerry, Windows Phone and more.

Threema is an end-to-end encrypted instant messenger allowing users to make voice calls, send text messages, share pictures and videos, etc. Threema application encrypts all of your online activity and it can be used completely anonymously, so your personal data will not be tracked by others.

TeamSpeak 3 provides the ideal service for keeping instant touch with family and friends and online education, gaming, and training, internal business communication. What makes it outstanding among similar apps is that it's simple to operate with high security standards, amazing voice quality, and low system and bandwidth usage. With a client-server architecture, TeamSpeak 3 is literally capable of handling up to thousands of users simultaneously.

Developed by Joya Communications, Marco Polo Video Walkie Talkie allows you to make fun videos and keep in touch with your friends. Just push the button and start talking with your best friends.

Slack introduces a new way to get more done and spend less time in meetings. All your team communication in one place.

Developed by ThienTinhGabo, Free Facetime Video Call Chat is a communication application which offers users a wide range of chat features including messaging, audio/video calls, push notifications and file transfer for free. With Facetime Video Call, users can stay in touch with their family and friends frequently through the high-quality video & voice calls, group chat and more other features.