Crabapples can be edible but come in two varieties. There is the ornamental crabapple that is less than 2 inches in diameter and not edible, and then there is the edible fruit that is larger than 2 inches in diameter and is edible.
Crabapples have been used in jellies, jams, sauces and pickling for years. Many older cookbooks have recipes using crabapples. The most common use for crabapples is in jellies due to the naturally high level of pectin. In crabapple jellies, there are usually four basic ingredients: crabapples, water, sugar and cinnamon. Other versions might incorporate additional fruits and other flavors.