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.
GETGetEventStatsForAccount
https://api.steampowered.com/IEconDOTA2_570/GetEventStatsForAccount/v1/
NameValueTypeRequiredDescription
uint32 Yes The Event ID of the event you're looking for.
uint32 Yes The account ID to look up.
string NoThe language to provide hero names in.
GETGetHeroes
https://api.steampowered.com/IEconDOTA2_570/GetHeroes/v1/
NameValueTypeRequiredDescription
string NoThe language to provide hero names in.
bool NoReturn a list of itemized heroes only.
GETGetItemCreators
https://api.steampowered.com/IEconDOTA2_570/GetItemCreators/v1/
NameValueTypeRequiredDescription
uint32 Yes The item definition to get creator information for.
GETGetItemWorkshopPublishedFileIDs
https://api.steampowered.com/IEconDOTA2_570/GetItemWorkshopPublishedFileIDs/v1/
NameValueTypeRequiredDescription
uint32 Yes The item definition to get published file ids for.
GETGetRarities
https://api.steampowered.com/IEconDOTA2_570/GetRarities/v1/
NameValueTypeRequiredDescription
string NoThe language to provide rarity names in.
GETGetTournamentPrizePool
https://api.steampowered.com/IEconDOTA2_570/GetTournamentPrizePool/v1/
NameValueTypeRequiredDescription
uint32 NoThe ID of the league to get the prize pool of