Miunlocktool is used to flash stock ROM Firmware and install custom ROMs. It’s an official tool of xiaomi developers, so it supports for almost every xiaomi mobile devices.
Before flashing your device, you will have to unlock your bootloader. to do that you need to install your mobile phone drivers to your pc. So use below link to download it.
Then you will need to install the MI Unlock tool to unlock your bootloader. Use below link to download it.
Now you need to download MI Flash tool to flash your mobile device and install a new custom ROM
We have provided all the links from Xiaomi official website. So you won’t get any kind of malware or virus.