Bitcoin testnet

https://en.bitcoin.it/wiki/Testnet

bitcoind

 -port=<port>
      Listen for connections on <port>. Nodes not using the default ports
      (default: 8333, testnet: 18333, signet: 38333, regtest: 18444)
      are unlikely to get incoming connections. Not relevant for I2P
      (see doc/i2p.md).

• Testnets: Sepolia, Goerli, Ropsten, Prater, Kiln, Kintsugi, Rinkeby, Kovan, Holesky (2023), Bitcoin testnet, --network
• bitcoind, .bitcoin/, bitcoin.conf, Dockerfile, Bitcoind ports( 8332 18332 18443 8333 18333 18444 ), -chain, -datadir, -server, --help, Bitcoind logs, Bitcoind changelog
• Bitcoin (BTC), Bitcoin Cash (BCH), Wrapped Bitcoin (WBTC), blockchain.com, Coinbase, Cryptocurrency wallet, Ripple, Grayscale, Hummingbot, USD Coin, Zcash, Polkadot, bitcoin-cli, BSV, Bitmain, Hal Finney, List of bitcoin forks, Lightning Network, Minsc, SegWit, Bitcoin mining, BIP, Bech32, Ordinals, SPV, Bitcoin testnet, Satoshi Nakamoto, BRC-20, Bitcoin genesis block, Bitcoin address