Storage queries reference

Each item described here is a StorageDescriptor<Args, ReturnType, Optional, Opaque>
For example, System.Account is of type

Account: StorageDescriptor<[Key: SS58String], {
consumers: number;
data: {
flags: bigint;
free: bigint;
frozen: bigint;
reserved: bigint;
};
nonce: number;
providers: number;
sufficients: number;
}, false, "never">

and can be queried via

const account = await api.query.System.Account.getValue("<AccountId>")
console.log(account.data.free)

PAPI docs on storage queries for more

Namespaces

Alliance
AllianceMotion
AmbassadorCollective
AmbassadorContent
AmbassadorCore
AmbassadorReferenda
AmbassadorSalary
AssetRate
Aura
AuraExt
Authorship
Balances
CollatorSelection
FellowshipCollective
FellowshipCore
FellowshipReferenda
FellowshipSalary
FellowshipTreasury
MessageQueue
Multisig
ParachainInfo
ParachainSystem
PolkadotXcm
Preimage
Proxy
Scheduler
Session
StateTrieMigration
System
Timestamp
TransactionPayment
XcmpQueue