flexCard 0.5 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this free software for Mac is Dancing Tortoise Software. FlexCard for Mac lies within Education Tools, more precisely Teaching Tools.
From the developer:
A new take on flash card management. Dealing with a large and varied deck has never been easier.
Intuitive searching and sorting: Quickly find the flash cards you wish to review. Need to review all of the verbs introduced in chapter 10 for an upcoming language test? Select chapter 10 and verb in the category pane and only those cards that match both will be visible.
You may want to check out more software for Mac, such as PianoRoll, eduMap or FRS Money Math, which might be similar to flexCard.