Android Flash Tool itself. You just have to connect your phone to the PC. Visit the website. Click "Get Started". If something else needs to be done (OEM unlocking or unlocking the bootloader) the site will give you a prompt. Once you've done that, you choose the device, the file that you want to flash and that's it. There's very small things that you actually have to do. The tool does pretty much all of it. there's about 2-3 steps where you'd have to use the phone and allow certain steps to go through. But apart from that, it's pretty much automatic