Some good iPhone apps for carb counting include Carbs Control, Daily Carb and Low Carb Diet Assistant. Each app has a four-star or higher user rating in the App Store, as of July 2015.
These apps are similar in that they all feature a food database that returns serving sizes, calories and carbohydrate counts. All three apps allow the user to log food consumption in a daily journal and to set goals for carbohydrate and calorie consumption. The app developers market the apps toward users with diabetes or people who are on low-carb diets for weight loss. Daily Carb features a unique function that allows users to export dietary journals to CSV, HTML or PDF files for medical use.