PartsBox is an online app that lets you take control of your electronic parts inventory, BOM pricing, and small-scale production. It keeps track of where components are stored, what the current stock levels are, and which components are used in which projects/BOMs. In addition, PartsBox provides always up-to-date BOM pricing and offer management.
Been using it for more than a year to keep track of the components we buy and what components we are missing. Especially helpful since we don't consume all we order for a build when there is a issue and we save the components for later.