Heavdrones are HTech devices used for monitoring and control of various systems. They communicate with various control backends using SPUDNET. In all likelihood, you're viewing this through a heavdrone right now, whether you know it or not.
The first heavdrones were deployed on ComputerCraft in the Unicode Consortium, and could provide information about connected peripherals to a web interface. The heavdrone web interface was soon rewritten due to being bad, as well as the heavdrone protocol and heavdrone heavdevice code.