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

Aura
AuraExt
Authorship
Balances
BridgeKusamaGrandpa
BridgeKusamaMessages
BridgeKusamaParachains
BridgeRelayers
CollatorSelection
EthereumBeaconClient
EthereumInboundQueue
EthereumOutboundQueue
EthereumSystem
MessageQueue
Multisig
ParachainInfo
ParachainSystem
PolkadotXcm
Session
System
Timestamp
TransactionPayment
XcmpQueue