Yes Mayo is gluten free and dairy free. My husband liked the Hellmans but Kraft is also gluten-free/cf. He is now doing a gluten-free/cf/sf diet so we had to ditch the regular Hellmans but today I found that Hellmans has a Canola Mayo (no soy)

. The lays stax are gluten free but only the plain is gluten-free/cf but again its not soy free. I thought it was going to really hard to eliminate the casein along with gluten but there are still alot of food choices and now even after having to eliminate the soy in addition I'm finding plenty of food choices for him. I just read alot of labels in the store. There are list on this forum that give the names of mainstream companies that will clearly list all common food allergens in the ingredients. These list are very helpful. I don't know how to send them to you or I would but they are on here.
Good Luck.
Jennifer