I am looking for free restaurant inventory software. Is stock an extra charge with you?

No. Dish counts, ingredients, recipes, food cost, suppliers, purchase orders, stock-takes and waste are included in every plan, from the smallest upwards, and there is nothing to switch on. During the fifteen day free trial you have all of it with no card. There is also nothing to install: the pages live under Menu in your dashboard and work in a phone browser. What is not free is the POS add-on, and stock does not need it. A cook can still mark a dish off from the kitchen screen if you have one, and your ordering page stops selling a counted dish at zero either way. The Stock, recipes and suppliers tab in the docs shows every screen.