A tool to update and launch tf2classic. This tool was created all the way back in 2019 and started getting used for the first time by beta testers in October 2019. It provided them and currently the public a way of updating the game in a relatively easy fashion by simply pressing an update button.
This tool works by incrementally applying archives which contain changed files. The tool is also capable of removing files, allowing files to be renamed or content to be removed.
There also exists a separate tool called tf2c-updater which is a command line utility which implements the same behavior in C++ using libcurl and libarchive.