Bigbasket.com
I ordered some groceries and not easily perishable vegetables from Bigbasket.com. This decision was out of curiosity to try an online grocery delivery option and it offered a 20% discount. The objective of ordering online grocery is primarily saving time and effort when your budget through both alternatives is same. Time is a scare resource and with increasing demands on your time such services makes sense.
The main risks are that you cannot check the quality of the staple beforehand and the ease of return that a local kirana store provides. My experience with Bigbasket was good. All products were of good quality(I ordered only dry and packaged stuff). They delivered in time. Also with mobile app you can order anytime and choose the delivery slot.