The 23-year-old is regarded as one of the best talents outside the top two divisions and was named the League Two Player of the Year last season.
Ritchie was a key figure in Swindon's promotion to League One and has carried that form into this season after scoring nine goals for Paolo Di Canio's side.
He was rewarded with a new one-year contact back in September and is currently tied to the County Ground until the end of next season.
However, he is again attracting interest from other clubs after being the subject of a £500,000 offer from Bournemouth during the last January transfer window.
It is understood that Palace are interested in taking Ritchie to Selhurst Park as Ian Holloway looks to guide the club to promotion to the Premier League.