This app was mentioned in 2 comments, with an average of 9.00 upvotes
There's a pretty cool little app you can use to scan the lid of a egg carton and it shows you whether the eggs are really free range (limit of 1500 chooks per hectare) or not.
https://play.google.com/store/apps/details?id=au.com.choice.newthings.cluckar&hl=en
(It's made by Choice by the way, so it's legit.)
There's an appChoice magazine made that will scan the carton and tell you if they are being 100% honest or not.