Hi Amy

Like Nick above, we primarily use UTM links that feed into our Google Analytics, which is all free.

When you are generating your QR codes, instead of using just the final webpage as the link, instead create a UTM link that allows you to enter all sorts of parameters. Ie. you can be specific with location, campaign, etc if you want to track each board separately.
The link Nick shared is the same that I use and pretty self-explanatory.

In Google Analytics, you can then use filters based on those parameters.