Thank you for feedback. * You are right interface provide too much. My aim is not only provide deals. I mostly use it myself for books search. For technical books I always search for English books which are published in recent years (2 years) I saved my search parameters so I don't enter again again these. Sometimes I want to sort products by most reviews but this sort is absent in most departments. * Hidden keywords are not much fancy I agree. Sometimes I use it to find more results like wrote a nonsense word with minus "-dgeygdeuydgede" Amazon gives more results. * It against of Amazon terms of service.