Here are several options used as substitutes for baking soda in baking or cooking.

Baking powder contains both an acid and a base, so it can leaven baked goods without requiring an additional acidic ingredient.

Buttermilk is acidic and can react with baking powder to provide leavening in recipes that call for baking soda.

Sour milk is milk that has been soured with vinegar or lemon juice, can sometimes replace baking soda, particularly in recipes where acidity is needed for leavening.

Club soda contains carbon dioxide, can sometimes be used in recipes where baking soda provides leavening.

In some recipes, especially cakes, whipped egg whites incorporate air into the batter, can be used to provide leavening.

Yeast is primarily used as a leavening agent in bread and certain baked goods, it produces carbon dioxide gas through fermentation, which helps dough rise.

Potassium Bicarbonate is similar to baking soda, it can be used as a leavening agent in baking.