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.
UNDOCUMENTEDPOSTAddChatBan

Set the ban for a specific broadcaster. The issuer is the logged in steam account

https://api.steampowered.com/ISteamTVService/AddChatBan/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No
fixed64 No
uint32 No
bool No
bool No
UNDOCUMENTEDPOSTAddChatModerator

Add or remove a moderator for this broadcast channel

https://api.steampowered.com/ISteamTVService/AddChatModerator/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No
fixed64 No
bool No
UNDOCUMENTEDPOSTAddWordBan

Add or remove a banned keyword in this broadcast channel chat

https://api.steampowered.com/ISteamTVService/AddWordBan/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No
string No
bool No
UNDOCUMENTEDPOSTAppCheer

The user is cheering for a specific broadcast for a specific app.

https://api.steampowered.com/ISteamTVService/AppCheer/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
uint32 NoApp ID this cheer is for.
fixed64 NoThe thing being cheered on. ID is app dependent (could be steam id, match id, lobby id, server id, etc).
CSteamTV_AppCheer_SingleCheerType[] NoThe set of cheers this request represents (could be multiple of different types).
uint32 No
uint32 No
UNDOCUMENTEDPOSTCreateBroadcastChannel

Create a channel on SteamTV

https://api.steampowered.com/ISteamTVService/CreateBroadcastChannel/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
string NoUnique short broadcast channel name, part of Steam.TV URL
UNDOCUMENTEDPOSTFollowBroadcastChannel

Follow a broadcast channel

https://api.steampowered.com/ISteamTVService/FollowBroadcastChannel/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID
bool NoIndicates this is an unfollow request

Get list of broadcaster info for this channel

https://api.steampowered.com/ISteamTVService/GetBroadcastChannelBroadcasters/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID

Get broadcast channel clips

https://api.steampowered.com/ISteamTVService/GetBroadcastChannelClips/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No

Get a broadcast channel ID for a channel by name or owner SteamID

https://api.steampowered.com/ISteamTVService/GetBroadcastChannelID/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
string NoChannel short name)

Get broadcast channel images

https://api.steampowered.com/ISteamTVService/GetBroadcastChannelImages/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID
EBroadcastImageType Nolist of EBroadcastImage
int32[] Nolist of EBroadcastImage

Get user's interaction status with a broadcast channel

https://api.steampowered.com/ISteamTVService/GetBroadcastChannelInteraction/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID

Get broadcast channel profile data

https://api.steampowered.com/ISteamTVService/GetBroadcastChannelProfile/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID

Get broadcast channel live status

https://api.steampowered.com/ISteamTVService/GetBroadcastChannelStatus/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID
UNDOCUMENTEDGetChannels

Get the list of featured broadcast channels

https://api.steampowered.com/ISteamTVService/GetChannels/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
EGetChannelsAlgorithm NoThe algorithm to use when picking channels to return
uint32 NoThe maximum number of results to return
uint32 NoFilter results to only this appid
UNDOCUMENTEDGetChatBans

Get list of bans for a specific broadcaster.

https://api.steampowered.com/ISteamTVService/GetChatBans/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No
UNDOCUMENTEDGetChatModerators

Returns the list of moderators for this broadcast channel

https://api.steampowered.com/ISteamTVService/GetChatModerators/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No

Get list of followed channels by a viewer

https://api.steampowered.com/ISteamTVService/GetFollowedChannels/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
UNDOCUMENTEDGetGames

Get list of games with active broadcasters

https://api.steampowered.com/ISteamTVService/GetGames/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
uint32 NoThe ID for the game
EGetGamesAlgorithm NoThe algorithm to use when picking games to return
uint32 NoThe maximum number of results to return

Returns homepage contents for user

https://api.steampowered.com/ISteamTVService/GetHomePageContents/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key

Gets the broadcast channels that the current user owns

https://api.steampowered.com/ISteamTVService/GetMyBroadcastChannels/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key

Returns a user's SteamTV settings

https://api.steampowered.com/ISteamTVService/GetSteamTVUserSettings/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key

Get list of channels a user is subscribed to

https://api.steampowered.com/ISteamTVService/GetSubscribedChannels/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
UNDOCUMENTEDGetWordBans

Returns the list of banned keywords for this broadcast channel

https://api.steampowered.com/ISteamTVService/GetWordBans/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No
UNDOCUMENTEDPOSTJoinChat

Joins the chat channel for a broadcast

https://api.steampowered.com/ISteamTVService/JoinChat/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No
UNDOCUMENTEDPOSTReportBroadcastChannel

Report a broadcast channel

https://api.steampowered.com/ISteamTVService/ReportBroadcastChannel/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID
string NoThe reason for the report
UNDOCUMENTEDPOSTSetBroadcastChannelImage

Set broadcast channel image hash

https://api.steampowered.com/ISteamTVService/SetBroadcastChannelImage/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID
EBroadcastImageType NoEBroadcastImage
uint32 NoIndex of the image (for supporting multiple uploads of the same type
uint32 Nowidth in pixels
uint32 Noheight in pixels
uint32 Noin bytes
string Noeg .jpg
string Noimage SHA
bool Noindicates this is a delete request

Set broadcast channel link regions

https://api.steampowered.com/ISteamTVService/SetBroadcastChannelLinkRegions/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID
CSteamTV_SetBroadcastChannelLinkRegions_Request.Links[] No
uint32 No
string No
string No
uint32 No
uint32 No
uint32 No
uint32 No

Set broadcast channel profile data

https://api.steampowered.com/ISteamTVService/SetBroadcastChannelProfile/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID
string Nolong channel name
string Noprimary channel language (Steam shortname)
string Noshort channel desciption
string Nolong channel desciption
string Nocommunity avatar hash
string Nobroadcast channel schedule
string Nobroadcast channel rules
string NoJSON data representing the channel panel layout
UNDOCUMENTEDPOSTSetSteamTVUserSettings

Sets a user's SteamTV settings

https://api.steampowered.com/ISteamTVService/SetSteamTVUserSettings/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
bool NoSend email when followed stream starts
bool NoSend Steam notification when followed stream starts

Subscribe to a broadcast channel

https://api.steampowered.com/ISteamTVService/SubscribeBroadcastChannel/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 NoBroadcast channel ID