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.
UNDOCUMENTEDPOSTApproveFeatureAccess

Approve or deny temporary access to a feature from a child account

https://api.steampowered.com/IParentalService/ApproveFeatureAccess/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
bool NoApprove or deny temporary access to a feature from a child account
fixed64 No
uint32 NoApprove or deny temporary access to a feature from a child account
uint32 NoApprove or deny temporary access to a feature from a child account
fixed64 No
UNDOCUMENTEDPOSTApprovePlaytime

Approve or deny a temporary playtime request from a child account

https://api.steampowered.com/IParentalService/ApprovePlaytime/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
bool No
fixed64 No
ParentalTemporaryPlaytimeRestrictions No
ParentalPlaytimeDay No
uint64 No
uint32 No
uint32 No
fixed64 No
UNDOCUMENTEDPOSTDisableParentalSettings

Disable parental settings for the logged in account

https://api.steampowered.com/IParentalService/DisableParentalSettings/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
string No
fixed64 No
UNDOCUMENTEDPOSTEnableParentalSettings

Enable parental settings for the logged in account, optionally setting the current settings

https://api.steampowered.com/IParentalService/EnableParentalSettings/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
string No
ParentalSettings No
fixed64 No
uint32 No
string No
ParentalApp[] No
uint32 No
bool No
ParentalApp[] No
uint32 No
bool No
uint32 No
bytes No
bytes No
bool No
uint32 No
string No
bool No
uint32 No
uint32 No
ParentalPlaytimeRestrictions No
bool No
ParentalPlaytimeDay[] No
uint64 No
uint32 No
ParentalTemporaryPlaytimeRestrictions No
ParentalPlaytimeDay No
uint64 No
uint32 No
uint32 No
uint32[] No
uint32[] No
uint32[] No
string No
uint32 No
fixed64 No

Get the current parental settings for the logged in account

https://api.steampowered.com/IParentalService/GetParentalSettings/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
fixed64 No
UNDOCUMENTEDGetRequests

Return a list of pending (or pending and completed) feature and playtime requests for the given steamid

https://api.steampowered.com/IParentalService/GetRequests/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
uint32 NoReturn a list of pending (or pending and completed) feature and playtime requests for the given steamid
fixed64 NoReturn a list of pending (or pending and completed) feature and playtime requests for the given steamid
fixed64 No

Get the current parental settings for the logged in account in a form that can by verified by the receiver

https://api.steampowered.com/IParentalService/GetSignedParentalSettings/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
uint32 No
UNDOCUMENTEDPOSTLockClient

Notify connected clients that a lock has occurred in a browser

https://api.steampowered.com/IParentalService/LockClient/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
string No
UNDOCUMENTEDPOSTRequestFeatureAccess

Request temporary access to a feature from a parent account

https://api.steampowered.com/IParentalService/RequestFeatureAccess/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
uint32 NoRequest temporary access to a feature from a parent account
fixed64 No
UNDOCUMENTEDPOSTRequestPlaytime

Request temporary additional playtime from a parent account

https://api.steampowered.com/IParentalService/RequestPlaytime/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
uint32 NoRequest temporary additional playtime from a parent account
ParentalPlaytimeDay NoRequest temporary additional playtime from a parent account
uint64 No
uint32 No
fixed64 No
UNDOCUMENTEDPOSTRequestRecoveryCode

Request a recovery code be sent to the recovery email address for the specified account

https://api.steampowered.com/IParentalService/RequestRecoveryCode/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
UNDOCUMENTEDPOSTSetParentalSettings

Set the current parental settings for the logged in account

https://api.steampowered.com/IParentalService/SetParentalSettings/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
string No
ParentalSettings No
fixed64 No
uint32 No
string No
ParentalApp[] No
uint32 No
bool No
ParentalApp[] No
uint32 No
bool No
uint32 No
bytes No
bytes No
bool No
uint32 No
string No
bool No
uint32 No
uint32 No
ParentalPlaytimeRestrictions No
bool No
ParentalPlaytimeDay[] No
uint64 No
uint32 No
ParentalTemporaryPlaytimeRestrictions No
ParentalPlaytimeDay No
uint64 No
uint32 No
uint32 No
uint32[] No
uint32[] No
uint32[] No
string No
string No
fixed64 No
UNDOCUMENTEDPOSTValidatePassword

Validate the plaintext password for the logged in account and return an unlock token

https://api.steampowered.com/IParentalService/ValidatePassword/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
string No
string No
bool No
UNDOCUMENTEDPOSTValidateToken

Check if the given parental unlock token is correct for the logged in account

https://api.steampowered.com/IParentalService/ValidateToken/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
string No