As well as the ExifTool Updates (https://exiftool.org/rss.xml) RSS feed, I have just added a new file to the ExifTool web server that may be used to determine the current ExifTool version:
https://exiftool.org/ver.txt
This file consists of a single line with the version number of the latest official ExifTool release (with no trailing newline), and may be useful for applications which automatically check for ExifTool updates.
- Phil