Arc Mainnet Is Live: Chain ID, RPC & First Steps

Arc's public mainnet is live as of September 16, 2026 — Circle's stablecoin Layer-1 is open to everyone, with USDC as gas, sub-second finality, and a validator set that includes BlackRock, Visa, and Mastercard. This page has the verified network parameters, the fastest wallet setup, your first bridge, and the safety warnings that matter most in launch week. Bookmark it: the parameters below update the moment Circle publishes anything new.

What is live on Arc mainnet today

Arc mainnet is scheduled to open on 16 September 2026. Nothing is live on Circle's Arc mainnet before that date — every integration named so far is announced, on testnet, or exploratory, and any page or post claiming a live Arc mainnet deployment today is describing testnet at best. This section will carry the observed count and names from the morning of the 16th; the checked list, with the evidence behind each status, is maintained at Built on Arc's live list.

The gap between those two numbers is the whole story of launch week, and it is not a criticism of anyone. Being named in a press release, running on testnet since October 2025 and having a contract deployed to mainnet are three different states, and only the third is checkable by a stranger. When you see a project described as "live on Arc", the question worth asking is which of the three is meant.

How to check a claim yourself

Three checks settle almost every case, in about two minutes.

1. Find the mainnet contract address or endpoint the project publishes. A testnet address is not evidence of a mainnet deployment. If a project's docs still show only 5042002 values, it is on testnet.
2. Look it up on the official mainnet explorer. Confirm the explorer URL against docs.arc.io first — Circle had not published mainnet RPC or explorer URLs as of 6 September 2026, and a fake "official" explorer is the cheapest scam to run in a launch week. Copy the URL from Circle's own documentation; never from a post, a DM or a search ad.
3. Check whether the project has said so itself. A counterparty naming you is weaker evidence than you naming yourself. Where only Circle has spoken, treat it as announced.

Status changes — a project moving from testnet to mainnet, an integration going live, an announced name going quiet — are logged daily at builtonarc.app/updates, which is the fastest way to see what has moved since you last looked.

What are Arc's mainnet parameters?

The verified network details for Arc mainnet:

Take these values only from this page, arc.io, or circle.com. Launch week is peak season for fake "Arc mainnet RPC" posts that route your wallet through an attacker's endpoint — a wrong RPC can feed you false balances and bait transactions. The testnet (chain ID 5042002, rpc.testnet.arc.io) remains live and separate; the testnet guide covers it.

How do you add Arc mainnet to your wallet?

In MetaMask: Settings → Networks → Add network → Add a network manually, then enter the name, chain ID, RPC URL, symbol (USDC), and explorer from the table above and save. That's the whole setup — about a minute. The full MetaMask guide covers one-click adds from apps and hardware-wallet pairing, and the wallet comparison covers Ledger, Binance Wallet, and Fireblocks, all in Arc's day-one lineup.

One display quirk to expect on day one: some wallets label the native balance "ETH" out of habit. The balance is USDC — the number is right, the ticker is cosmetic.

How do you get USDC onto Arc mainnet?

Via CCTP, Circle's native transfer protocol, from Ethereum, Base, Solana, and other supported chains — no wrapped assets, no third-party bridge risk. The quickstart: open the bridge guide, select your source chain, send USDC to Arc, and it arrives as native USDC — the same asset that pays your gas. There is no separate gas token to buy: the first USDC you bridge funds everything you'll do. Fees on Arc run at cents or below (testnet averaged ~$0.004 per transaction), so a small first bridge goes a long way.

What should you do first — and what should you not do?

Worth doing in your first session: send a small test transfer before any large one (how sending works); look yourself up on the explorer so you know how to verify your own transactions; and if you're launching a project, start the launch checklist from step one rather than racing to deploy on day one — the chain isn't going anywhere, and launches that skip the trust steps get filtered by Arc's diligence-heavy audience.

Now the warnings, because launch day is when scammers work hardest:

There is still no ARC token. Mainnet going live does not change this. Circle's whitepaper describes an exploratory coordination asset; no token has launched and no airdrop has been announced. Every "ARC" token trading today — including any that appear on Arc itself this week — is counterfeit. The full story.

Expect fake airdrops and fake faucets. Mainnet has no faucet — faucets are a testnet thing. Any site offering "mainnet Arc airdrops" or asking you to connect a wallet to "claim launch rewards" is phishing.

Verify before you buy anything. New chains attract instant scam tokens. Run the 5-minute safety checklist on any token before buying, and take contract addresses only from projects' official channels.

FAQ

When did Arc mainnet launch? September 16, 2026. The public testnet had been live since October 28, 2025 and continues to operate separately.

What is Arc's mainnet chain ID? See the table above — this page carries the verified value ([MAINNET-TBD] until Circle's official publication, updated the moment it lands). Cross-check against arc.io before trusting any other source.

Do I need a new wallet for mainnet? No — the same wallet works. Mainnet is a separate network entry alongside testnet; add it with the parameters above. Testnet balances are valueless rehearsal assets and do not carry over.

What does gas cost on Arc mainnet? Gas is paid in USDC and dollar-denominated by design. Testnet fees averaged around $0.004 per transaction; mainnet fees are visible in your wallet before each transaction confirms.

Is there an Arc airdrop for mainnet users? No airdrop has been announced, and no ARC token exists. Treat every airdrop claim site as phishing until Circle itself says otherwise — announcements come from arc.io and circle.com only.