I have a large number of .pdf files with much the same headers and footers that I’d like to remove.
Is there a something that can remove everything up to a known string and everything after a different known string leaving a valid .pdf?
Didn't try this however, since it is only for Windows afaik.
The other way you could do this is by using OCR, and there a lots of different apps and ways to do this: Tesseract is one of them. (work on windows, mac and un*x)
You need to add more detail to your post, since it does not say what operating system it is targeted for, or ways you would want to do this (script, gui app, etc).