I use ScoutIQ for my book scanning needs. Many people also like Scoutly. You absolutely need one of these apps to be competitive and successful selling books. I do not recommend using the Amazon Seller App or eBay as your primary scanning app. ScoutIQ has a Live version and a Database plus Live version. The Live version does a current lookup of the item you’re scanning while the Database version downloads a database of Amazons inventory and compares the item you scan to what it says in the downloaded database. The main reason to have the Database version is that if there’s no internet access in the location where you’re scanning you will still get a result to know if the book is profitable or not. The Live version requires internet access. Without internet access, you won’t know if the book is profitable or not. These days, because I’m so infrequently scanning books I just keep the Live version. It’s around $10 a month while the Database version is $40-$50 a month.
Once you have a pile of books, you then need to list your products for sale on Amazon. The best, and most efficient way to list over the years is through Accelerlist.
If you get serious with selling books, in the future I would highly recommend purchasing Keepa. Keepa dives deeper into sales and price history of any item listed for sale on Amazon. Sometimes ScoutIQ and Scoutly aren’t able to tell the full story of a book for you, Keepa will “complete the last chapter” so to speak. Is it needed? When you’re a beginner, no not really. If you really want to know the business it is needed. I would say pass on it for now.
I have included affiliate links to the products I recommend, you don’t have to use them but I would appreciate it you did. Regardless, I think it’s good to help others and share information.