Arc chain ID 5042: the official network details
Everything a wallet or a script needs to talk to Arc, taken from Circle's documentation and repository, with the mainnet cells left blank until Circle fills them. Plus the reason you should not trust any other source for this table.
| Parameter | Mainnet | Testnet |
|---|---|---|
| Network name | Arc | Arc Testnet |
| Chain ID (decimal) | 5042 | 5042002 |
| Chain ID (hex) | 0x13b2 | 0x4cef52 |
| Gas token | USDC, 18 decimals as gas, 6 as ERC-20 | USDC, 18 decimals as gas, 6 as ERC-20 |
| Official RPC | not yet published | rpc.testnet.arc.io (also Blockdaemon, dRPC and QuickNode mirrors listed by Circle) |
| Explorer | walled until launch | testnet.arcscan.app |
| Faucet | n/a | faucet.circle.com |
| USDC system contract | 0x3600000000000000000000000000000000000000 | 0x3600000000000000000000000000000000000000 |
| CCTP V2 domain | 26 | 26 |
| Multicall3 | 0xcA11bde05977b3631167028862bE2a173976CA11 (testnet; mainnet addresses not yet published) | 0xcA11bde05977b3631167028862bE2a173976CA11 |
Circle's docs state that all published contract addresses are for the testnet and that mainnet addresses are not yet available. This page will carry the mainnet RPC and addresses the day Circle publishes them, and not before. The testnet hex ID is the value the chain itself returns to eth_chainId.
A chain ID is a label your wallet writes on the tab. The RPC decides which chain you are actually talking to. Since the gated mainnet went live, guides have circulated with "add network" buttons pointing at endpoints that are not Circle's, at least one of which has been accused of serving a fork that reports chain 5042. A public chain directory also lists an unrelated "ARC Mainnet" at chain IDs 1243 and 1244. None of those is Arc.
The rules that keep you safe are short. Add the network only from Circle's documentation. Pull the genesis from Circle's repository if you want to verify an endpoint yourself. Run any endpoint through the RPC checker, which reads its chain ID, block zero, the USDC system contract and its block cadence and compares them with Circle's published parameters. And confirm any balance on a second, independent reader before acting on it.
What the checker cannot do yet is prove identity. Only a block-zero hash compared against a final genesis published by Circle can, and Circle's repository still holds placeholders. That comparison will be added the day the final genesis lands.
Fees follow EIP-1559 with an exponentially weighted moving average on the base fee, so a short burst of traffic does not spike the fee for the next block. On the testnet the base fee floor is 20 gwei and the ceiling 20,000 gwei, with a design target of roughly a cent per ordinary transaction. Priority fees of zero are accepted. Circle notes these values may change before mainnet.
USDC on Arc has two faces. As gas it is accounted in 18 decimals, like ETH on Ethereum. As an ERC-20 at 0x3600…0000 it has the usual 6 decimals. A wallet that shows a custom gas token needs its display set to 18, and a script that reads balances needs to know which interface it is calling. Circle's documentation says the same.
- Connect to Arc, Circle documentation - network names, chain IDs, RPC and WebSocket endpoints, explorer, faucet
- Contract addresses, Circle documentation - USDC, EURC, CCTP V2, Gateway and Multicall3 on testnet; mainnet not yet published
- Gas and fees, Circle documentation
- circlefin/arc-node mainnet genesis - chain ID 5042 and the USDC system contract in the genesis alloc
Chain facts on this page come only from Circle. Where a figure is the site's own reading, the terminal card it comes from is linked. Definitions are on the method page.