This page is just a reference of all the known Steam APIs, I do not know how they work. Please do not email me with questions.
UNDOCUMENTEDGetFantasyPlayerRawStats
https://api.steampowered.com/IDOTA2Fantasy_570/GetFantasyPlayerRawStats/v1/
UNDOCUMENTEDGetPlayerInfo
https://api.steampowered.com/IDOTA2Fantasy_570/GetPlayerInfo/v1/
UNDOCUMENTEDGetPlayerInfos
https://api.steampowered.com/IDOTA2Fantasy_570/GetPlayerInfos/v1/
UNDOCUMENTEDGetProPlayerInfo
https://api.steampowered.com/IDOTA2Fantasy_570/GetProPlayerInfo/v1/