HTML Tidy  5.6.0
The HTACG Tidy HTML Project
Application Notes

Of course, there are functions to parse and save both markup and configuration files. For the adventurous, it is possible to create new input sources and output sinks. For example, a URL source could pull the markup from a given URL.

It is also worth remembering that an application may instantiate any number of document and buffer objects. They are fairly cheap to initialize and destroy (just memory allocation and zeroing, really), so they may be created and destroyed locally, as needed. There is no problem keeping them around a while for keeping state. For example, a server app might keep a global document as a master configuration. As documents are parsed, they can copy their configuration data from the master instance. See tidyOptCopyConfig(). If the master copy is initialized at startup, no synchronization is necessary.