There are about 150 UPI apps in India. Years ago, choosing one was hard. But is there any difference? Isn't the underlying work the same for all? Aren't they just different flavours? True to some extent, but some of these apps provide some extra functionality over or along with UPI, which sometimes is a huge differentiating factor, and this integration of these functionalities made me call it a stack. This stack makes payments easier, and that is what this blog is about.