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.
UNDOCUMENTEDGETGetCurrentClientConnections
https://api.steampowered.com/ISiteLicenseService/GetCurrentClientConnections/v1/
NameValueTypeRequiredDescription
click to setstring Yes Steamworks Web API publisher authentication key
uint64 NoSite ID to see; zero for all sites
UNDOCUMENTEDGETGetTotalPlaytime
https://api.steampowered.com/ISiteLicenseService/GetTotalPlaytime/v1/
NameValueTypeRequiredDescription
click to setstring Yes Steamworks Web API publisher authentication key
string Yes Report activity starting on or after this time. RFC 3339 UTC format.
string Yes Report activity starting before this time. RFC 3339 UTC format.
uint64 NoSite ID to see; zero for all sites