Hi, I use a few apps, but again they are mainly food diary type apps. Carbs and Cals has their own app (I got it for around £3 on the apple app store), there's one called low carb tacker that I have on my phone, but havent use it. My fitness pal is fairly good as they go, and so is the food diary on the argus fitness tracking app. THere are lots out there that perform as food diaries, but to be honest I would recommend looking through the app store and checking out the free apps and deciding ether the app suits you or not, with the exception of the carbs and cals app (which yes you can add new foods to).