Brayford has established himself as a key player at Derby since his arrival from Crewe in the summer of 2010.
The 25-year-old is regarded as one of the best full-backs outside the Premier League and Derby are bracing themselves for bids for Brayford at the end of the season.
Brayford had an ever-present role in the Derby side this season until he picked up a hamstring injury in March, but the talented defender is now back to full fitness after making a quicker than expected return to action.
Cardiff are thought to be long-term admirers of Brayford, having been linked with a move for the right-back during the January transfer window, and they could rekindle that interest in the player as they plan for life in the Premier League next season.
The likes of West Ham, Stoke and Wigan are also thought to be keeping tabs on Brayford as they look to bolster their defensive options next season.