A great egg substitute for use in baking is Ener-G brand Egg Replacer. It contains no egg whatsoever and is also free of wheat and gluten, dairy, casein, soy, yeast, nut and rice. Be aware that some major brand whole egg substitutes are made from eggs but are marketed to appeal to those who are trying to reduce dietary intake of fat and cholesterol. It works great in cooking and baking.
The products are still made from eggs so if there is an allergy or intolerance those products may not be of any benefit. If there is an intolerance to either the yolk or the white, products that are made of the part of the egg one is not having a problem with may be of benefit.
Can I Use Duck, Goose, Turkey, or Quail Eggs Instead of Chicken Eggs?
These types of eggs may be worth a try if there is an egg intolerance to chicken eggs but still an overwhelming desire to consume eggs. This doesn’t fix the issue of the processed foods that contain components of eggs from chickens though – it will only help if you are doing the cooking. Also, it is most likely that if there is an intolerance to eggs from one species that there will be an intolerance of the eggs from another species.