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This quickstart gets you to a running geth instance with the JSON-RPC API exposed locally. By the end you’ll be able to query the chain, create an account, and connect a wallet.

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Step 1. Build the binary

If you haven’t already, follow Installation to produce build/bin/geth.

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Step 2. Connect to mainnet

./build/bin/geth \
  --networkid 20803 \
  --datadir ~/.quantum-chain \
  --syncmode snap \
  --http \
  --http.addr 127.0.0.1 \
  --http.port 8545 \
  --http.api eth,net,web3,debug \
  --ws \
  --ws.addr 127.0.0.1 \
  --ws.port 8546 \
  --ws.api eth,net,web3
The first sync downloads the chain. Snap sync usually completes in a few hours on a fast machine. Verify it works: 
curl -s -X POST http://127.0.0.1:8545 \
  -H "Content-Type: application/json" \
  --data '{"jsonrpc":"2.0","method":"eth_chainId","id":1,"params":[]}'
# → {"jsonrpc":"2.0","id":1,"result":"0x5143"}    # 0x5143 = 20803

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Step 3 (alternative). Run a local devnet

For development you don’t need to sync mainnet. Run a single-node Clique network with pre-funded accounts.

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Create a genesis file

Save the following as devnet.json: 
{
  "config": {
    "chainId": 20803,
    "homesteadBlock": 0,
    "eip150Block": 0,
    "eip155Block": 0,
    "eip158Block": 0,
    "byzantiumBlock": 0,
    "constantinopleBlock": 0,
    "petersburgBlock": 0,
    "istanbulBlock": 0,
    "berlinBlock": 0,
    "londonBlock": 0,
    "quantumVerificationBlock": 0,
    "clique": { "period": 5, "epoch": 30000 }
  },
  "difficulty": "1",
  "gasLimit": "30000000",
  "extraData": "0x0000000000000000000000000000000000000000000000000000000000000000<SEALER_ADDRESS_NO_0X>0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  "alloc": {}
}
Replace <SEALER_ADDRESS_NO_0X> with a 40-character hex address of the validator you’ll create in step 4.

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Initialize the data directory

./build/bin/geth --datadir ./devnet init devnet.json

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Start the devnet

./build/bin/geth \
  --datadir ./devnet \
  --networkid 20803 \
  --mine \
  --miner.etherbase 0x<SEALER_ADDRESS> \
  --unlock 0x<SEALER_ADDRESS> \
  --password ./password.txt \
  --allow-insecure-unlock \
  --http --http.api eth,net,web3,debug,personal \
  --http.corsdomain "*"
Blocks seal every 5 seconds. The eth_blockNumber JSON-RPC call should advance.

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Step 4. Create an account

Use the post-quantum keygenerator: 
./build/bin/keygenerator --passphrase "strong-pass"
The output includes:
  • A 12-word mnemonic for recovery.
  • A post-quantum public key (large hex blob).
  • The derived address (20 bytes, hex).
  • A keystore file in your working directory.
Copy the keystore file into ./devnet/keystore/ so geth can unlock it. See Accounts and keys for details.

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Step 5. Send a transaction

If you funded the address in alloc (or it’s the validator collecting block rewards), you can send a transaction. The simplest path is to use a wallet that supports external signing. Direct personal_sendTransaction is supported on devnets, but for production you should use Clef or Qustody. 
curl -s -X POST http://127.0.0.1:8545 \
  -H "Content-Type: application/json" \
  --data '{
    "jsonrpc":"2.0",
    "method":"eth_getBalance",
    "params":["0x<YOUR_ADDRESS>","latest"],
    "id":1
  }'

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Where to go next

Configuration

Genesis fields, geth flags, and tuning.

Accounts and keys

How post-quantum keypairs and addresses work.

Networks

Mainnet, testnets, and running a validator.

Integrate with Qustody

Use the custody platform for institutional workflows.