I'm sorry I've this has been posted somewhere and I've missed it.
Are there any already-written tools out there for monitoring/reporting the balance of multiple addresses (Masternodes)?
I use this
https://drk.mn/masternodes.html(a lot of copy/pasting involved)
I wish there was a proper app or something to monitor multiple MN's !
Anybody

Excel... use an embeded web query to
https://drk.mn/masternodes.html, on a second sheet, put your column of addresses, append the [1][2][3] to the addresses into another column, then vlookup that value. Set the web query to refresh however often you like. I have mine setup to show balance, node revenue (balance - 1000), and up time.