Unikey is among the top 5 widely used and popular open-source software for typing in Vietnamese. It is the official software used in schools as regulated by the Ministry of Education and Training.
Unikey was developed by Pham Kim Long in 1994. Initially known as a Vietnamese typing tool written in assembly language for the Dos operating system. By 1990, he had adapted it for compatibility with the Windows operating system. It wasn't until 2000 that he released it under the name Unikey, providing free support to users.
Unikey supports 14 Vietnamese encoding systems such as Unicode, TCVN3(ABC), VIQR, VNI...

Unikey enables users to utilize the three most common typing methods today: Telex, VNI, VIQR.

It allows users to seamlessly switch between encoding systems using the Clipboard.

During the Unikey installation process, it's essential to determine the bit version of your computer's operating system to select the appropriate Unikey version.
To determine your operating system's bit version, right-click on My Computer -> Properties, and find out the bit version of the operating system under System type:

Once you've determined your operating system's bit version, choose the appropriate Unikey version.
+ If you're using Windows 64-bit -> download Unikey 64-bit version.
+ If you're using Windows 32-bit -> download Unikey 32-bit version.
- The latest version of Unikey is Unikey 4.2 RC4. You can download the latest version on Unikey's official website:
http://www.unikey.org/bdownload.php
During the download process, ensure to select the Unikey version corresponding to your computer's operating system bit:

Download link for Unikey for 32-bit operating system:
https://nchc.dl.sourceforge.net/project/unikey/unikey-win/4.0%20RC2/unikey40RC2-1101-win32.zip
Download link for Unikey for 64-bit operating system:
Here's the detailed guide on how to Download Unikey, the latest version of Unikey. Wish you all success!