Bitcoin Core RPC

The Bitcoin Core RPC is the JSON-RPC interface that every modern Bitcoin Core node exposes for programmatic access. Wallets, block explorers, Lightning nodes, Electrum servers, and basically every Bitcoin service runs against an RPC connection to a backing Bitcoin Core node.

Connection basics:

• Default port is 8332 for mainnet, 18332 for testnet, 38332 for signet. Configurable via rpcport in bitcoin.conf.
• Authentication is via either an rpcauth line in the config (preferred, hashes the password) or a generated cookie file in the data directory. Username / password in cleartext is supported but discouraged.
• Format is JSON-RPC 1.0 over HTTP. Each call is a single HTTP POST with a method name and parameters.

The standard CLI driver is bitcoin-cli, which wraps RPC in a shell-friendly interface. bitcoin-cli getblockchaininfo is roughly equivalent to curl -X POST -d '{"jsonrpc":"1.0","method":"getblockchaininfo","params":[]}' http://user:pass@localhost:8332/.

The RPC surface is enormous. Categories you'll see in practice:

• Blockchain queries. getblock, getblockhash, getblockchaininfo, getbestblockhash, getrawtransaction.
• Wallet operations. sendtoaddress, getbalance, listunspent, listtransactions, signrawtransactionwithwallet, walletprocesspsbt.
• Mempool inspection. getmempoolinfo, getrawmempool, getmempoolentry.
• Network state. getpeerinfo, getconnectioncount, getnetworkinfo.
• Mining helpers. getblocktemplate, submitblock, getmininginfo.
• Diagnostic. getmemoryinfo, gettxoutsetinfo, validateaddress.

Security: the RPC is by default bound to localhost only. Exposing it to the network without TLS and strong authentication is a fast way to lose any wallet attached to the node. For remote management of a home node, the standard pattern is JSON-RPC over Tor - an unguessable .onion address, encrypted transport, no firewall holes. The rpcwhitelist setting in modern versions lets operators restrict each authenticated user to a specific subset of methods, which is the right pattern for multi-tenant setups (a block explorer doesn't need wallet RPC access; restrict accordingly).

For users of Bitcoin-on-top services, the RPC is invisible plumbing. For anyone running infrastructure - exchanges, payment processors, Lightning routing nodes - it's the daily working surface of Bitcoin Core.