Touchcards and Cardboard can import Google Docs spreadsheets as flashcards. One benefit to using Google Docs is that you can keep your decks safe in the cloud. You can also share them with others and manage changes more easily.
To make sure your spreadsheets are imported properly, use the following formats. You can paste the URL to an image instead of text if you want to have the app import a photo.
The first row is a header row and isn't imported. The columns correspond to question and answer. Note if you're having trouble importing a set, try leaving the first row blank rather than having text like "front" and "back" or similar.
You can provide multi-line answers if you need to.
You can add worksheets to your spreadsheet document. Each worksheet is a set of flashcards.