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.
UNDOCUMENTEDGETGetChangedDatesForPartner
https://api.steampowered.com/IPartnerFinancialsService/GetChangedDatesForPartner/v1/
NameValueTypeRequiredDescription
click to setstring Yes Steamworks Web API publisher authentication key
uint64 Yes A unique identifier, the point at which to query data forward from. Should be set to 0 on first run.
bool NoInclude dates that are visible via view grants in the response
UNDOCUMENTEDGETGetDetailedSales
https://api.steampowered.com/IPartnerFinancialsService/GetDetailedSales/v1/
NameValueTypeRequiredDescription
click to setstring Yes Steamworks Web API publisher authentication key
string Yes Date to retrieve the sales data for. The date should be formatted as YYYY-MM-DD, YYYY/MM/DD, or YYYYMMDD.
uint64 Yes A per-date value (ie. should be set at 0 for each date being queried). Informs the number of new records to query for.
bool NoInclude sales data that is visible via view grants in the response