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.
UNDOCUMENTEDGetPrivateAppList
https://api.steampowered.com/IAccountPrivateAppsService/GetPrivateAppList/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
UNDOCUMENTEDPOSTToggleAppPrivacy
https://api.steampowered.com/IAccountPrivateAppsService/ToggleAppPrivacy/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
bool No
int32[] No