JSON-RPC

Armchain exposes a standard Ethereum-compatible JSON-RPC API over HTTP and WebSocket. If you've used Ethereum's JSON-RPC before, everything works the same way: same method names, same parameters, same response format.

Endpoint

HTTP:      http://localhost:18545   (or https://www.armchain.org/devnet for devnet)
WebSocket: ws://localhost:18546     (or wss://www.armchain.org/devnet for devnet)

Request Format

curl -X POST <RPC_URL> \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "<METHOD>",
    "params": [<PARAMS>],
    "id": 1
  }'

---

eth Namespace

eth_blockNumber

Returns the latest block number.

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

Response:

{"jsonrpc":"2.0","id":1,"result":"0x1a4"}

---

eth_getBalance

Returns the balance of an address in wei.

Parameters:

1. address: 20-byte address
2. blockTag: Block number or "latest", "earliest", "pending"

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_getBalance","params":["0xADDRESS","latest"],"id":1}'

Response:

{"jsonrpc":"2.0","id":1,"result":"0xde0b6b3a7640000"}

---

eth_getTransactionCount

Returns the number of transactions sent from an address (nonce).

Parameters:

1. address: 20-byte address
2. blockTag: Block number or tag

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_getTransactionCount","params":["0xADDRESS","latest"],"id":1}'

---

eth_sendRawTransaction

Submits a signed transaction for broadcast.

Parameters:

1. data: Signed transaction data (hex). Must be a Type 3 PQC transaction.

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_sendRawTransaction","params":["0x03f9..."],"id":1}'

Response:

{"jsonrpc":"2.0","id":1,"result":"0xTRANSACTION_HASH"}

---

eth_call

Executes a call without creating a transaction (read-only).

Parameters:

1. transaction: Transaction call object
2. blockTag: Block number or tag

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{
    "jsonrpc":"2.0",
    "method":"eth_call",
    "params":[{
      "to": "0xCONTRACT_ADDRESS",
      "data": "0x70a08231000000000000000000000000ADDRESS"
    }, "latest"],
    "id":1
  }'

---

eth_estimateGas

Estimates gas for a transaction.

Parameters:

1. transaction: Transaction call object

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{
    "jsonrpc":"2.0",
    "method":"eth_estimateGas",
    "params":[{
      "from": "0xFROM",
      "to": "0xTO",
      "value": "0xde0b6b3a7640000"
    }],
    "id":1
  }'

---

eth_getBlockByNumber

Returns block information by block number.

Parameters:

1. blockNumber: Block number (hex) or tag
2. fullTransactions: If true, returns full transaction objects

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_getBlockByNumber","params":["latest", false],"id":1}'

---

eth_getTransactionByHash

Returns transaction details by hash.

Parameters:

1. transactionHash: 32-byte transaction hash

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_getTransactionByHash","params":["0xHASH"],"id":1}'

Response (Type 3 PQC Transaction):

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "type": "0x3",
    "hash": "0x...",
    "from": "0x...",
    "to": "0x...",
    "value": "0xde0b6b3a7640000",
    "nonce": "0x1",
    "gasLimit": "0x5208",
    "maxFeePerGas": "0x4a817c800",
    "maxPriorityFeePerGas": "0x77359400",
    "chainId": "0x37",
    "blockNumber": "0x1a4",
    "blockHash": "0x...",
    "transactionIndex": "0x0"
  }
}

---

eth_getTransactionReceipt

Returns the receipt of a mined transaction.

Parameters:

1. transactionHash: 32-byte transaction hash

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_getTransactionReceipt","params":["0xHASH"],"id":1}'

---

eth_getLogs

Returns logs matching a filter.

Parameters:

1. filter: Filter object with fromBlock, toBlock, address, topics

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{
    "jsonrpc":"2.0",
    "method":"eth_getLogs",
    "params":[{
      "fromBlock": "0x0",
      "toBlock": "latest",
      "address": "0xCONTRACT",
      "topics": ["0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"]
    }],
    "id":1
  }'

---

eth_chainId

Returns the chain ID.

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}'

Response:

{"jsonrpc":"2.0","id":1,"result":"0x37"}

---

eth_gasPrice

Returns the current gas price.

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_gasPrice","params":[],"id":1}'

---

eth_getCode

Returns the code at a given address (for contracts).

Parameters:

1. address: Contract address
2. blockTag: Block number or tag

curl -X POST https://www.armchain.org/devnet -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_getCode","params":["0xCONTRACT","latest"],"id":1}'

---

Other Standard Methods

Method	Description
eth_accounts	Returns list of owned addresses
eth_sign	Signs data with account key
eth_signTransaction	Signs a transaction without sending
eth_getBlockByHash	Get block by hash
eth_getTransactionByBlockHashAndIndex	Get tx by block hash and index
eth_getTransactionByBlockNumberAndIndex	Get tx by block number and index
eth_getStorageAt	Get storage value at position
eth_syncing	Returns sync status
eth_mining	Returns whether node is mining/validating
eth_coinbase	Returns validator address

---

net Namespace

Method	Description
net_version	Returns network ID
net_listening	Whether node is listening for connections
net_peerCount	Number of connected peers

---

web3 Namespace

Method	Description
web3_clientVersion	Returns client version string
web3_sha3	Returns Keccak-256 of input

---

txpool Namespace

Method	Description
txpool_status	Returns pending and queued tx counts
txpool_content	Returns all pending and queued txs
txpool_inspect	Returns textual summary of pool

---

personal Namespace

Warning: Only use on local/private nodes. Never expose on public endpoints.

Method	Description
personal_newAccount	Create a new account
personal_unlockAccount	Unlock an account for signing
personal_lockAccount	Lock an account
personal_listAccounts	List all accounts
personal_sendTransaction	Sign and send a transaction

---

admin Namespace

Method	Description
admin_nodeInfo	Returns node information
admin_peers	Returns connected peers
admin_addPeer	Add a peer by enode URL
admin_removePeer	Remove a peer
admin_datadir	Returns the data directory path

---

WebSocket Subscriptions

Subscribe to New Blocks

// eth_subscribe: newHeads
ws.send(JSON.stringify({
  jsonrpc: "2.0",
  method: "eth_subscribe",
  params: ["newHeads"],
  id: 1
}));

Subscribe to Logs

// eth_subscribe: logs
ws.send(JSON.stringify({
  jsonrpc: "2.0",
  method: "eth_subscribe",
  params: ["logs", {
    address: "0xCONTRACT",
    topics: ["0xTOPIC_HASH"]
  }],
  id: 1
}));

Subscribe to Pending Transactions

ws.send(JSON.stringify({
  jsonrpc: "2.0",
  method: "eth_subscribe",
  params: ["newPendingTransactions"],
  id: 1
}));

Unsubscribe

ws.send(JSON.stringify({
  jsonrpc: "2.0",
  method: "eth_unsubscribe",
  params: ["SUBSCRIPTION_ID"],
  id: 2
}));

---

Rate Limits

Public RPC endpoints may enforce rate limits.

Further Reading

• Armchain-Specific APIs: DAG and PQC-specific endpoints
• Network Configuration: Endpoints and chain details