Zalo is a Vietnamese instant messaging multi-platform service developed by VNG Corporation. Zalo is also used in other countries outside of Vietnam, including the United States, Japan, South Korea, Australia, Germany, Myanmar and Singapore.

As of late September 2024, Zalo has approximately 77.6 million active monthly users with nearly 1.97 billion messages sent each day. Zalo is currently available in all 34 provinces and municipalities of Vietnam, including islands, remote areas, and is accessible in more than 23 countries worldwide.

The name for Zalo is a blend of Zing (an online website managed by VNG) and alo (a standard phrase used to answer a call in Vietnam).

Zalo was created by Vương Quang Khải, the executive Vice President of VNG. After studying in the United States, he returned to Vietnam in 2007. Recently, he began to work primarily on Artificial Intelligence technology, developing Kiki, an AI based virtual assistant.

The first software test version of Zalo was released in August 2012, eight months after development began in late 2011. By September 2012, Zalo had released new versions on iOS, Android and the Nokia S40. However, Zalo received little recognition due to various user issues, including having to use Zing ID for login and utilizing web platforms for the mobile application.

In December 2012, the official version for Zalo was released to the public. On 8 January 2013, Zalo reached the top spot on the App Store in Vietnam, passing their main competitor, WeChat.

In March 2013, Zalo reached the million-user milestone and continued to grow quickly, having over 2 million users only two months later, surpassing all international competitors, including Viber and Line.

Zalo has continuously been adding new features, such as Short videos, enhanced privacy features and other improvements to the software.