Open the can of crab and put it in a large bowl, fluffing it up with a fork.
Add the cracker crumbs and use a fork or spatula to stir together the crab and crackers until well combined.
In a smaller bowl, whisk together the mayonnaise, egg yolk, parsley, lemon juice, Worcestershire sauce, mustard, melted butter, Harissa and salt. Add this mixture to the crab and cracker mixture and mix gently until well-combined.
Using a small whisk, vigorously whip the egg white for a minute or two until the white is filled with air and very frothy, similar to a meringue. Gently fold the whipped egg white into the crab mixture until combined.
Use a large cookie scoop (about two scoops each) to evenly divide the crab mixture into six cakes. Place them on a plate and refrigerate the crab cakes for about 10 minutes to let them set up a bit.
Place the crab cakes in the air fryer basket (my basket fit four at a time). Air fry the crab cakes at 375 degrees F for about 12 minutes, or until they are nicely browned.