Categorizing cards is a feature we are working on for a future update.
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 A solution we have found that has worked for other users is the 'Notes' feature. For example, if you add '#sales' as a personal note to a Haystack card, you can find that card again by typing '#sales' into the search box at the top of the app.
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 To add a personal note:
 1. Tap on the card you want to categorize
 2. Scroll down to the bottom of the card
 3. Type the category you want to add it to in the 'Notes' box
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