This website was developed by Leigh Dodds.
It was generated using an open source tool called overpass-doc which is designed to support the publication of collections of OverpassQL queries. It provides a simple command-line interface for generating documentation from packages of Overpass queries.
The source files are all in github and are in the public domain.
The syntax highlighting code was adapted from the Overpass Turbo code which is published under an MIT Licence.