The closest we've got is the unofficial http://www.spellbookbuilder.com/. I think it's missing the latest Academy sets though (Druid, Necromancer, Elementalist and Monk).
Thank you for letting me know about that.
Without something like the Gatherer website or other software available for games like Magic: The Gathering to track inventory and create decks from their inventory, how do most people create decks in Mage Wars or keep track of their cards? Complex Excel files?
At spellbookbuilder.com, if you click the "show sets" link at the upper right, you can choose the quantity of each set/expansion that you own. This will then correctly give you the right card counts (in the "own" column).
To create decks, you can use the "show spellbook" and increase the value in the "used" column to build a deck, then export to file or text.