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.
GETGetNewsForAppv2
https://api.steampowered.com/ISteamNews/GetNewsForApp/v2/
NameValueTypeRequiredDescription
uint32 Yes AppID to retrieve news for
uint32 NoMaximum length for the content to return, if this is 0 the full content is returned, if it's less then a blurb is generated to fit.
uint32 NoRetrieve posts earlier than this date (unix epoch timestamp)
uint32 No# of posts to retrieve (default 20)
string NoComma-separated list of feed names to return news for
string NoComma-separated list of tags to filter by (e.g. 'patchnodes')
PUBLISHERGETGetNewsForAppAuthedv2
https://partner.steam-api.com/ISteamNews/GetNewsForAppAuthed/v2/
NameValueTypeRequiredDescription
click to setstring Yes access key
uint32 Yes AppID to retrieve news for
uint32 NoMaximum length for the content to return, if this is 0 the full content is returned, if it's less then a blurb is generated to fit.
uint32 NoRetrieve posts earlier than this date (unix epoch timestamp)
uint32 No# of posts to retrieve (default 20)
string NoComma-seperated list of feed names to return news for
string NoComma-separated list of tags to filter by (e.g. 'patchnodes')