@nixCraft originally my hard drive.
Then some source control system that I never understood and that as far as I could tell ran on a PC that was under my boss’ desk. A nightmare this was!
Then I convinced the boss to let me install and configure git (including some post receive hooks that would automatically deploy to production) and ssh on one of our dedicated servers (we were an IIS house at the time, so neither came pre-installed).
I was so proud of myself at the time, but I think GitHub came about a few months later, so my system didn’t live for very long…