Border Buddy is a Blender add-on from SimonThommes that helps preserve render borders. It lives in a panel in the output properties, where the render border you set in camera view can be captured and kept for later use.
To store a border, press '+', give the snapshot a name, and it joins a list. Selecting an entry from that list retrieves the saved border again. The workflow stays inside the output properties panel.
Border Buddy is compatible with Blender 4.2 LTS and newer, and requires no special permissions to run. It's distributed through Blender Extensions, where you can drag and drop the file into Blender or install it from disk. The add-on is released under the GNU General Public License v2.0 or later, with source available on the developer's GitLab page. Version 0.1.1 fixed a crash.