The Historical Data API has a request rate limit of 100 requests in 10 seconds.
Any requests that breach this limit will return a HTTP 429 Too Many Request error.
All of the below requests (including any errors returned) are included in the 100 requests limit. All requests are summed up within a 10 second period.
GetMyData- Returns the packages you have purchased
GetCollectionOptions- Returns the filter options for a give filter
DownloadListOfFiles- Returns a list of files based on a filter
GetAdvBasketDataSize- Returns a file count and size based on a filter
DownloadFile- Downloads a specific file