I wasn’t able to easily find information on how to add USB bootloader support. I have compiled my findings and hopefully you will find this very useful.

PLEASE READ:
This video is now a year and a half old. I have a new version of the video here:
   • How to Install the STM32 USB Bootload...  

The dan drown stm32 link below that I used in the video is now old. There are multiple versions of the STM32 core now, this is the newest version, but may be incompatible with what is shown in the video. I am working on a new version of the video.

STM32 "Blue Pill" Discord, join for easy access to likeminded developers
  / discord  

Add this to your Additional URLs under File/Preferences (OLD, BUT SHOULD STILL WORK):
http://dan.drown.org/stm32duino/packa...

Links:
Flash Loader:
https://goo.gl/e1mqwt

Drivers:
https://goo.gl/WB1TzB

Binaries:
https://goo.gl/kLJT21

Serial Adapter:
Amazon:
https://goo.gl/H9hdFb

Ebay:
https://goo.gl/aNzgew



Song:
Prototyperaptor Awe Listen to the track here:
https://spoti.fi/2HwfxDh