If it is this app, I have it and use it.
I had an email exchange with the developer and the name is somewhat of a misnomer. Although establishments with "No Open Carry" policies are technically not "gun free" they qualify for a red "No Guns" vote instead of green. They need to add a "comments" field though. There are a few "gun free" places on the app that don't outwardly appear to prohibit carry. There was also one that posted "No Open Carry" that had two "green" votes to my single "red" which is why I asked the developer what his opinion was.