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.
UNDOCUMENTEDPOSTCancelDailyDeal
https://api.steampowered.com/IDailyDealService/CancelDailyDeal/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No
UNDOCUMENTEDPOSTCreateDailyDeal
https://api.steampowered.com/IDailyDealService/CreateDailyDeal/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
CDailyDeal No
fixed64 No
int32 Noenum
uint32 No
string No
uint32 No
uint32 No
uint32 No
uint32 No
string No
string No
string No
bool No
bool No
uint32 No
fixed64 No
string No
uint32 No
uint32 No
fixed64 No
UNDOCUMENTEDPOSTDeleteDailyDeal
https://api.steampowered.com/IDailyDealService/DeleteDailyDeal/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No
UNDOCUMENTEDGetDailyDeals
https://api.steampowered.com/IDailyDealService/GetDailyDeals/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No
uint32 No
uint32 No
uint32 No
int32 Noenum
string No
uint32 No
https://api.steampowered.com/IDailyDealService/GetDailyDealsForApps/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
uint32[] No
UNDOCUMENTEDPOSTUpdateDailyDeal
https://api.steampowered.com/IDailyDealService/UpdateDailyDeal/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
CDailyDeal No
fixed64 No
int32 Noenum
uint32 No
string No
uint32 No
uint32 No
uint32 No
uint32 No
string No
string No
string No
bool No
bool No
uint32 No
fixed64 No
string No
fixed64 No