Lightning Nodes

Bitcoin Node Developer Guide

Build applications on Bitcoin using Comet's Bitcoin Core integration.

Overview

Comet provides full Bitcoin Core RPC access for:

Wallet operations
Transaction management
Blockchain queries
Network monitoring

Supported Versions: Bitcoin Core 24.0+

Quick Start

Deploy Bitcoin Core

comet bitcoin deploy fastsync

RPC Access

Credentials:

comet bitcoin credentials --node_id <node_id><

Output:

jsonCopy{
  "rpc_host": "bitcoin.comet.dev",
  "rpc_port": 80,
  "rpc_user": "user_abc123",
  "rpc_password": "pass_xyz789"
}

Test Connection

bitcoin-cli -rpcconnect=bitcoin.comet.dev \
  -rpcport=80 \
  -rpcuser=user_abc123 \
  -rpcpassword=pass_xyz789 \
  getblockchaininfo

Wallet Management

Create Wallet

bitcoin-cli createwallet "my_wallet"

With Descriptors:

bitcoin-cli createwallet "my_wallet" false false "" false true

Parameters:

wallet_name: Wallet identifier
disable_private_keys: false (default)
blank: false (default)
passphrase: "" (optional)
avoid_reuse: false (default)
descriptors: true (recommended)

Load Wallet

bitcoin-cli loadwallet "my_wallet"

List Wallets

bitcoin-cli listwallets

Wallet Info

bitcoin-cli -rpcwallet=my_wallet getwalletinfo

Response:

jsonCopy{
  "walletname": "my_wallet",
  "walletversion": 169900,
  "balance": 0.05000000,
  "unconfirmed_balance": 0.00000000,
  "immature_balance": 0.00000000,
  "txcount": 15,
  "keypoolsize": 1000
}

Address Management

Generate Address

Legacy:

bitcoin-cli -rpcwallet=my_wallet getnewaddress "" "legacy"

SegWit:

bitcoin-cli -rpcwallet=my_wallet getnewaddress "" "p2sh-segwit"

Native SegWit (Bech32):

bitcoin-cli -rpcwallet=my_wallet getnewaddress "" "bech32"

Taproot (Bech32m):

bitcoin-cli -rpcwallet=my_wallet getnewaddress "" "bech32m"

Address Types

Type	Format	Example	Use Case
Legacy	P2PKH	1A1zP1...	Legacy compatibility
P2SH-SegWit	P2SH	3J98t1...	Wide compatibility
Native SegWit	Bech32	bc1qw5...	Lower fees
Taproot	Bech32m	bc1p5d...	Privacy, efficiency

Recommendation: Use Taproot (bech32m) for new applications.

Validate Address

bitcoin-cli validateaddress "bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4"

Get Address Info

bitcoin-cli -rpcwallet=my_wallet getaddressinfo "bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4"

Transaction Management

Send Bitcoin

Simple Send:

bitcoin-cli -rpcwallet=my_wallet sendtoaddress "bc1q..." 0.001

With Fee Control:

bitcoin-cli -rpcwallet=my_wallet sendtoaddress "bc1q..." 0.001 "" "" false true 10

Parameters:

address: Recipient address
amount: BTC amount
comment: "" (optional)
comment_to: "" (optional)
subtractfeefromamount: false (default)
replaceable: true (enable RBF)
conf_target: 10 (blocks)

Batch Transactions

bitcoin-cli -rpcwallet=my_wallet sendmany "" '{
  "bc1q...": 0.001,
  "bc1p...": 0.002,
  "3J98t...": 0.0015
}'

Create Raw Transaction

Step 1: List Unspent Outputs

bitcoin-cli -rpcwallet=my_wallet listunspent

Step 2: Create Transaction

bitcoin-cli createrawtransaction '[
  {"txid": "abc123...", "vout": 0}
]' '{
  "bc1q...": 0.001,
  "bc1p...": 0.0489
}'

Step 3: Sign Transaction

bitcoin-cli -rpcwallet=my_wallet signrawtransactionwithwallet "02000000..."

Step 4: Broadcast

bitcoin-cli sendrawtransaction "02000000..."

Transaction Details

bitcoin-cli -rpcwallet=my_wallet gettransaction "txid"

Response:

jsonCopy{
  "amount": 0.001,
  "confirmations": 6,
  "blockhash": "00000000...",
  "blockheight": 820450,
  "txid": "abc123...",
  "time": 1704537600,
  "details": [...]
}

List Transactions

bitcoin-cli -rpcwallet=my_wallet listtransactions "*" 10

UTXO Management

List Unspent

bitcoin-cli -rpcwallet=my_wallet listunspent 1 9999999

Filter by Amount:

bitcoin-cli -rpcwallet=my_wallet listunspent 1 9999999 '[]' true '{
  "minimumAmount": 0.001,
  "maximumAmount": 0.01
}'

Lock UTXO

bitcoin-cli -rpcwallet=my_wallet lockunspent false '[
  {"txid": "abc123...", "vout": 0}
]'

Unlock UTXO

bitcoin-cli -rpcwallet=my_wallet lockunspent true '[
  {"txid": "abc123...", "vout": 0}
]'

List Locked

bitcoin-cli -rpcwallet=my_wallet listlockunspent

Fee Management

Estimate Fee

bitcoin-cli estimatesmartfee 6

Response:

jsonCopy{
  "feerate": 0.00010000,
  "blocks": 6
}

Confirmation Targets:

1 block: ~10 minutes (high priority)
6 blocks: ~1 hour (standard)
144 blocks: ~24 hours (low priority)

Set Transaction Fee

bitcoin-cli -rpcwallet=my_wallet settxfee 0.0001

Replace-By-Fee (RBF)

Bump Fee:

bitcoin-cli -rpcwallet=my_wallet bumpfee "txid" '{"fee_rate": 25}'

Blockchain Queries

Block Info

Latest Block:

bitcoin-cli getblockcount

Block Hash:

bitcoin-cli getblockhash 820450

Block Details:

bitcoin-cli getblock "00000000000000000001..."

Block with Transactions:

bitcoin-cli getblock "00000000000000000001..." 2

Blockchain Info

bitcoin-cli getblockchaininfo

Key Fields:

chain: "main" or "test"
blocks: Current height
headers: Header count
verificationprogress: Sync progress (0-1)
pruned: Pruning status

Transaction Lookup

Get Raw Transaction:

bitcoin-cli getrawtransaction "txid" true

Decode Transaction:

bitcoin-cli decoderawtransaction "02000000..."

Mempool Operations

Mempool Info

bitcoin-cli getmempoolinfo

Response:

jsonCopy{
  "size": 5432,
  "bytes": 2456789,
  "usage": 8901234,
  "maxmempool": 300000000,
  "mempoolminfee": 0.00001000
}

Mempool Contents

bitcoin-cli getrawmempool

Verbose:

bitcoin-cli getrawmempool true

Mempool Entry

bitcoin-cli getmempoolentry "txid"

Network Information

Peer Info

bitcoin-cli getpeerinfo

Network Info

bitcoin-cli getnetworkinfo

Connection Count

bitcoin-cli getconnectioncount

Descriptors

Output Descriptors

Modern wallet standard for deterministic key derivation.

Generate Descriptor:

bitcoin-cli -rpcwallet=my_wallet getdescriptorinfo "wpkh([fingerprint/84'/0'/0']xpub.../0/*)"

Import Descriptor:

bitcoin-cli -rpcwallet=my_wallet importdescriptors '[{
  "desc": "wpkh([fingerprint/84h/0h/0h]xpub.../0/*)#checksum",
  "timestamp": "now",
  "active": true
}]'

List Descriptors:

bitcoin-cli -rpcwallet=my_wallet listdescriptors

PSBTs (Partially Signed Bitcoin Transactions)

Create PSBT

bitcoin-cli -rpcwallet=my_wallet walletcreatefundedpsbt '[]' '[{
  "bc1q...": 0.001
}]'

Process PSBT

bitcoin-cli -rpcwallet=my_wallet walletprocesspsbt "cHNidP8BAH..."

Finalize PSBT

bitcoin-cli finalizepsbt "cHNidP8BAH..."

Decode PSBT

bitcoin-cli decodepsbt "cHNidP8BAH..."

Multisig Wallets

Create Multisig Address

2-of-3 Multisig:

bitcoin-cli createmultisig 2 '[
  "pubkey1",
  "pubkey2",
  "pubkey3"
]' "bech32"

Response:

jsonCopy{
  "address": "bc1q...",
  "redeemScript": "5221...",
  "descriptor": "wsh(multi(2,...))"
}

Import Multisig

bitcoin-cli -rpcwallet=multisig_wallet importmulti '[{
  "desc": "wsh(multi(2,...))#checksum",
  "timestamp": "now",
  "watchonly": true
}]'

Backup & Recovery

Backup Wallet

bitcoin-cli -rpcwallet=my_wallet backupwallet "/path/to/backup.dat"

Dump Private Key

bitcoin-cli -rpcwallet=my_wallet dumpprivkey "address"

⚠️ Warning: Keep private keys secure. Never share.

Import Private Key

bitcoin-cli -rpcwallet=my_wallet importprivkey "private_key" "label" false

Dump Wallet

bitcoin-cli -rpcwallet=my_wallet dumpwallet "/path/to/wallet.txt"

Python Integration

Using python-bitcoinrpc

from bitcoinrpc.authproxy import AuthServiceProxy

rpc = AuthServiceProxy(
    "http://user:pass@bitcoin.comet.dev:8332"
)

# Get blockchain info
info = rpc.getblockchaininfo()
print(f"Block height: {info['blocks']}")

# Create address
address = rpc.getnewaddress("", "bech32m")
print(f"New address: {address}")

# Send transaction
txid = rpc.sendtoaddress(address, 0.001)
print(f"Transaction: {txid}")

Error Handling

from bitcoinrpc.authproxy import JSONRPCException

try:
    result = rpc.sendtoaddress("invalid_address", 0.001)
except JSONRPCException as e:
    print(f"RPC Error: {e.error['message']}")

JavaScript Integration

Using bitcoin-core

const Client = require('bitcoin-core');

const client = new Client({
  host: 'bitcoin.comet.dev',
  port: 8332,
  username: 'user_abc123',
  password: 'pass_xyz789'
});

// Get blockchain info
const info = await client.getBlockchainInfo();
console.log(`Block height: ${info.blocks}`);

// Create address
const address = await client.getNewAddress('', 'bech32m');
console.log(`New address: ${address}`);

// Send transaction
const txid = await client.sendToAddress(address, 0.001);
console.log(`Transaction: ${txid}`);

Best Practices

Use Descriptors: Modern wallet standard
Enable RBF: Allow fee bumping
Taproot Addresses: Better privacy and efficiency
Coin Control: Manage UTXOs explicitly
Fee Estimation: Use estimatesmartfee
Backup Regularly: Export wallet backups
Test on Testnet: Validate before mainnet
Handle Errors: Implement robust error handling

Security

RPC Security

Never expose RPC publicly: Use VPN or SSH tunnels
Strong passwords: Generate random credentials
IP whitelisting: Restrict access by IP
TLS encryption: Use HTTPS for RPC calls

Wallet Security

Encrypt wallets: Use encryptwallet
Backup seeds: Store recovery phrases securely
Cold storage: Keep large amounts offline
Multi-signature: Require multiple approvals

Troubleshooting

Common Issues

Connection Refused:

Verify RPC credentials
Check firewall settings
Confirm node is running

Insufficient Funds:

Check wallet balance
Verify UTXO availability
Account for transaction fees

Transaction Not Confirming:

Check fee rate
Use RBF to bump fee
Monitor mempool status

Debug Mode

bitcoin-cli -rpcwallet=my_wallet logging '["rpc"]'

Resources

Bitcoin Core RPC: https://developer.bitcoin.org/reference/rpc/
BIPs: https://github.com/bitcoin/bips
Comet API: https://api.comet.dev/docs/bitcoin
Support: support@comet.dev

Next Steps

Enable Bitcoin Core on your node
Create test wallet on testnet
Practice transaction creation
Implement error handling
Build production application

Syntax and Structure

Bitcoin Node Developer Guide

Bitcoin Node Developer Guide

Table of Contents