GwentDroid provides you with a list of all of the Gwent cards in The Witcher 3: The Wild Hunt, including the new cards that come with both expansions, Hearts of Stone and Blood and Wine.
Using this list you can check off the cards you have collected in the game, leaving you with a clear overview of which cards you need to find and how many are left. GwentDroid also gives you a handy percentage reference to the total cards of each set that you have, i.e 50%.
If you need help finding a card, simply long press/hold down the card you want information for to start a Google search for that card!
This application wouldn't violate any copyrights, all artwork used inside the application belongs to the creators of the game. All rights reserved.