ARC

GetBlock provides fast and reliable access to Arc nodes via JSON-RPC API. Connect to the ARC network without running your own infrastructure.

Arc is an open Layer 1 blockchain built by Circle (the company behind USDC), purpose-built for stablecoin finance, payments, and institutional use cases. Launched on public testnet in late 2025 with participation from 100+ institutions, including BlackRock, Visa, and HSBC, Arc takes a fundamentally different approach to gas economics: instead of a volatile native token, USDC is the network's native gas token, making transaction fees predictable and dollar-denominated.

Arc is fully EVM-compatible, runs on Circle's Malachite consensus engine for deterministic sub-second finality, and ships with a built-in FX engine for 24/7 PvP stablecoin settlement plus opt-in compliance-friendly privacy. The result is a chain optimized for real-world financial activity — cross-border payments, capital markets, eCommerce checkout, and tokenized credit — that retains the developer experience of Ethereum.

Key Features

USDC as Native Gas: Transaction fees paid in USDC (6 decimals, not 18) — eliminates crypto-volatility from fee budgets and enables dollar-denominated cost predictability
Malachite Consensus: Deterministic sub-second finality engineered for financial infrastructure standards — no probabilistic settlement windows
Full EVM Compatibility: Standard Ethereum JSON-RPC method set; deploy Solidity / Vyper contracts and use Hardhat, Foundry, ethers.js, viem, and web3.py without modification
Built-in FX Engine: Native on-chain currency exchange with 24/7 PvP (Payment versus Payment) settlement for stablecoin pairs
Opt-In Privacy: Compliance-friendly privacy primitives that institutions can selectively enable for confidential financial operations
Circle Ecosystem Integration: First-class support for CCTP (Cross-Chain Transfer Protocol), Paymaster, and Circle's broader stablecoin tooling
Sub-Second Block Times: ~2 second block production tuned for high-throughput payments and order-flow workloads
Institutional Backing: Designed with input from 100+ financial institutions — BlackRock, Visa, HSBC, and others
ERC-4337 & EIP-7702 Native: Account abstraction support built into the network for gas sponsorship, batched transactions, and smart accounts
AI Agent Primitives: Native support for AI agent registration and ERC-8183 job markets, enabling the agentic economy

TECHNICAL DISCLAIMER: AUTHORITATIVE JSON-RPC SPECIFICATION

GetBlock’s Arc API reference documentation is provided exclusively for informational purposes and to optimize the developer experience. The canonical and normative specification for the Ethereum JSON-RPC API is maintained by the Ethereum community and published at ethereum.org/en/developers/docs/apis/json-rpc/. For Arc-specific protocol details, consensus parameters, the FX engine, and the privacy layer, consult the official documentation at docs.arc.io.

USDC-DENOMINATED GAS — IMPORTANT

Arc uses USDC as its native gas token, with 6 decimals (not 18 like most EVM chains). When working with eth_getBalance, eth_gasPrice, eth_maxPriorityFeePerGas, eth_feeHistory, and transaction value fields, divide raw wei values by 10⁶ — not 10¹⁸ — to obtain USDC. This is the single most common integration mistake when porting an existing EVM dApp to Arc.

Network Information

Property

Value

Network Name

Arc Testnet

Stage

Public testnet (mainnet not yet launched)

Chain ID

5042002 (0x4cef52)

Native Currency

USDC

Decimals

6 (not 18 — see warning above)

Block Time

~2 seconds

Consensus

Malachite (deterministic sub-second finality)

Smart Contract VM

EVM (Ethereum Virtual Machine)

EVM Compatible

Yes (fully compatible)

Address Format

Ethereum-style (0x…, 20 bytes)

Block Explorer

testnet.arcscan.app

Faucet

faucet.circle.com

Base URL

https://go.getblock.io/<ACCESS-TOKEN>/

All Arc JSON-RPC methods are called by sending a POST request to the base URL with a standard JSON-RPC 2.0 body. For real-time subscriptions (new blocks, finalized heads, logs) use the WebSocket scheme: wss://go.getblock.io/<ACCESS-TOKEN>/.

Supported Networks

Network

JSON-RPC

WSS

Frankfurt, Germany

Testnet

✅

Arc mainnet has not yet launched. This documentation targets the public testnet (Chain ID 5042002), which is the current stable development environment.

Quickstart

In this section, you will learn how to make your first call with either:

Axios (JavaScript / Node.js)
Python (Requests library)

Before you begin, you must have already installed npm or yarn on your local machine (for the Axios example) or Python and pip (for the Python example).

Setup project

Create and initialize a new project:

mkdir arc-api-quickstart
cd arc-api-quickstart
npm init --yes

Install Axios

npm install axios

Create file

Create a new file named index.js. This is where you will make your first call.

Set ES module type

Set the ES module "type": "module" in your package.json.

Add code

Add the following code to index.js:

index.js

import axios from 'axios';

const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "eth_chainId",
    "params": [],
    "id": "getblock.io"
});

const config = {
    method: 'post',
    url: 'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers: {
        'Content-Type': 'application/json'
    },
    data: data
};

axios(config)
    .then(response => console.log(JSON.stringify(response.data, null, 2)))
    .catch(error => console.log(error));

Replace <ACCESS-TOKEN> with your actual access token from GetBlock.

Run the script

node index.js

Expected output:

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x4cef52"
}

The result field is the Arc testnet chain ID (0x4cef52 = 5042002 in decimal). This confirms you are connected to the correct network.

Setup the project directory

mkdir arc-api-quickstart
cd arc-api-quickstart

Create and activate a virtual environment

python -m venv venv
source venv/bin/activate

# On Windows, use venv\Scripts\activate

Install requests

pip install requests

Create script

Create a file called main.py with the following content:

main.py

import requests
import json

url = "https://go.getblock.io/<ACCESS-TOKEN>/"

payload = json.dumps({
    "jsonrpc": "2.0",
    "method": "eth_chainId",
    "params": [],
    "id": "getblock.io"
})

headers = {
    'Content-Type': 'application/json'
}

response = requests.post(url, headers=headers, data=payload)
print(response.text)

Replace <ACCESS-TOKEN> with your actual access token from GetBlock.

Run the script

python main.py

Available API Methods

Arc exposes the full standard Ethereum JSON-RPC method set. All methods are POST-only and called against the base URL above.

Block & Chain Information

Method

Description

eth_blockNumber

Returns the current latest block number

eth_chainId

Returns the chain ID (0x4cef52 = 5042002 for Arc testnet)

eth_getBlockByNumber

Returns block information by block number

eth_getBlockByHash

Returns block information by block hash

eth_getBlockTransactionCountByNumber

Returns the number of transactions in a block by block number

eth_getBlockTransactionCountByHash

Returns the number of transactions in a block by block hash

eth_getBlockReceipts

Returns all transaction receipts for a given block

eth_syncing

Returns sync status or false if node is fully synced

Account & State

Method

Description

eth_getBalance

Returns the USDC balance of an account (in 6-decimal base units)

eth_getCode

Returns the contract bytecode at a given address

eth_getStorageAt

Returns the value at a specific storage slot

eth_getProof

Returns the Merkle proof for an account and optional storage keys

eth_getTransactionCount

Returns the transaction count (nonce) for an account

Transactions

Method

Description

eth_sendRawTransaction

Broadcasts a signed transaction

eth_getTransactionByHash

Returns a transaction by its hash

eth_getTransactionByBlockHashAndIndex

Returns a transaction by block hash and index

eth_getTransactionByBlockNumberAndIndex

Returns a transaction by block number and index

eth_getTransactionReceipt

Returns the receipt for a transaction by hash

eth_call

Executes a read-only call against contract state

eth_estimateGas

Estimates gas required for a transaction (denominated in USDC base units)

Gas & Fee Market

Method

Description

eth_gasPrice

Returns the current gas price in USDC base units

eth_maxPriorityFeePerGas

Returns the suggested max priority fee per gas (EIP-1559, in USDC base units)

eth_feeHistory

Returns historical base fees and priority fees

Logs & Filters

Method

Description

eth_getLogs

Returns logs matching a given filter

eth_newFilter

Creates a new log filter

eth_newBlockFilter

Creates a filter that fires on new blocks

eth_newPendingTransactionFilter

Creates a filter that fires on new pending transactions

eth_getFilterChanges

Polls a filter for new events since the last poll

eth_getFilterLogs

Returns all logs matching a filter

eth_uninstallFilter

Uninstalls a filter

WebSocket Subscriptions

Method

Description

eth_subscribe

Subscribes to events (newHeads, logs, newPendingTransactions)

eth_unsubscribe

Cancels an existing subscription

Network & Client Info

Method

Description

net_version

Returns the network ID (5042002 for Arc testnet)

net_listening

Returns true if the client is actively listening for connections

net_peerCount

Returns the number of peers connected to the node

web3_clientVersion

Returns the client software version

web3_sha3

Returns the Keccak-256 hash of the given data

Support

For technical support and questions:

Support Email: [email protected]

Key Features

Network Information

Base URL

Supported Networks

Quickstart

Setup project

Install Axios

Create file

Set ES module type

Add code

Run the script

Setup the project directory

Create and activate a virtual environment

Install requests

Create script

Run the script

Available API Methods

Block & Chain Information

Account & State

Transactions

Gas & Fee Market

Logs & Filters

WebSocket Subscriptions

Network & Client Info

Support

See Also