This testnet. A running chain cannot change its id.
Network
The explorer is public. The node is not.
The testnet produces blocks on one machine. The explorer is the public window. The node's RPC, engine, and beacon ports are not.
testnet.kalyx.si reads the chain and shows blocks, accounts, and validators.
The explorer, the browser wallet, and the faucet are on testnet.kalyx.si. A new validator still runs a node of their own and deposits 40,000 KALYX. The network docs list which doors are public.
This network is not for value you cannot afford to lose. Client audits are not finished. The wallet on the explorer can send KALYX in public, move a private note, compile Solidity, and publish contract bytecode. The node's ports stay closed. Super Intelligence Validators are the written standard: a model may draft, and the key stays in a signer. The two genesis validators are ordinary stake.