Search cards using a big range of filters. You can search cards by color, commander color identity, manacost, name, type...
Deck building
Build your decks. The app will keep track of them including the sideboard.
You can import/export the deck in .dec format.
Up to date MTG database
MTG card database is from mtgjson.com. Probably the best source to get MTG data.
"MTGJSON is an open-source project that catalogs all Magic: The Gathering cards in a portable format. A dedicated group of fans maintains and supplies data for a variety of projects and sites in the community."