Circle opened the public mainnet of its Arc network on 16 September 2026. Below: what the network is, what actually happened that day, what already runs on it, and how much of that can be checked. The live state of the network, its connection parameters and the addresses of the venues sit on the Arc hub.
What Arc is
Arc is a Layer 1 blockchain built by Circle, the issuer of USDC, for stablecoin payments, foreign exchange and tokenized assets. Circle describes it with two properties: "predictable fees payable in stablecoins (starting with USDC)" and "sub-second transaction finality".
The launch material is equally plain about who it addresses: Arc is "for you if you're a developer", "a business" or "an institution". For individual users Circle points to Arc Portal (portal.arc.io): earn, swap, send and bridge.
What happened on 16 September
That day the chain opened to the public: Arc has been producing blocks since mid-May 2026, through a private mainnet in which Circle counted more than a hundred institutional and ecosystem builders.
The official explorer, explorer.arc.io, shows the chain from its first blocks along with contract creators, so a token’s age can be checked independently.
Connection parameters and the block explorer
Arc’s documentation lives at docs.arc.io rather than in the developer section of Circle’s own site. The chain ID is 5042, gas is paid in USDC, and the public RPC is served without a key; partner endpoints from Blockdaemon, dRPC and QuickNode return the same chain identifier. The exact addresses are on the hub, next to the date they were checked.
The official block explorer is explorer.arc.io, the one Circle’s documentation lists. Domains such as arc-scan and arcscan have nothing to do with Circle.
How to get USDC onto Arc
Several exchanges have opened USDC withdrawals to the Arc network; which ones, and at what fee and minimum, is in the table on the Arc hub, which follows exchange data. Withdrawal forms name the network in different ways: ARC, Arc Network, Arc. From another chain, USDC moves over CCTP or Circle Gateway — both run on mainnet.
Where USDC earns on exchanges today, with the date each rate was collected, is in a separate roundup.
What already runs on the chain
Uniswap’s official deployment list names Arc among its supported chains, with its own contract addresses there. Launchpads have appeared with their own tokens and their own DEXes, along with a venue that launches tokens paired with stock tokens, perpetuals on currency pairs, multichain bridges and a screener that already sees the network. Circle names Aero, fomo and Uniswap as the anchors of day-one trading, and Aave and Morpho as the anchors of the credit market; DefiLlama tracks Morpho, Aave and Uniswap on Arc.
Aero is the successor to Aerodrome, a brand from the Base network. Its contracts appeared on Arc on 15 September, and DefiLlama counts its Aerodrome Slipstream venue on the Arc network.
The venues’ mechanics — which one routes part of its fee into buying back its token, which one burns, which one pays holders — are set out on the Arc hub against primary sources: every row there carries a contract address and a link to the document describing that mechanic.
NFTs: the mints are real, the verifiable collections are few
A token with its own identifier representing a collectible, an in-game item or another digital asset. The blockchain records which address owns the token. on Arc are not announcements: the chain shows more than twenty ERC-721 contracts with fresh mints. But tying a claimed project to a contract is almost never possible — collection sites do not publish an address, and X profiles do not answer automated checks. Of the fifty collections circulating in the lists, only a handful can be tied to a contract; those are collected on the hub with their addresses.
The chain holds two different contracts with the same name, and neither of their supplies matches what the lists promise. Alongside a confirmed collection sits an almost identically named one with four times the supply. And ticker copies of well-known memes were minted on the very day the network opened, and the day before — while the originals date from July. Check the contract address, not the name and not the picture: the addresses of confirmed collections are on the hub, with links to the explorer.
The ARC token: sale, mint and status
Circle has published a whitepaper describing ARC as "the native coordination asset of the Arc network", covering staking and delegation toward a proof-of-stake transition, governance and fee mechanics.
In May 2026 Circle sold 740 million ARC to institutional investors led by a16z crypto at 30 cents per token — 222 million dollars at a network valuation of 3 billion dollars; the deal was disclosed in a Form 8-K filing. With a second closing at the end of June, 807.5 million tokens had been sold for 242.2 million dollars. The tokens are locked for at least a year after the network moves to proof-of-stake, and if that transition is not completed by 8 May 2028, the buyers are entitled to demand their money back.
In the mainnet launch week Circle minted the full initial supply of 10 billion ARC and stated that the mint is not a commitment to launch the token publicly. On 17 September the token page on arc.io still reads "ARC is not launched". Gas on the network remains in USDC. Circle has announced no airdrop and no participation rules for users.
Arc and Base, for someone who holds USDC
The comparison people reach for is Base, since both chains are closely tied to USDC. They are not the same kind of object. Base is an Ethereum Layer 2, open to everyone for years, where gas is paid in ETH and exchanges that support the network already allow withdrawals to it. Arc is a Layer 1 whose validator set is permissioned, whose fees are charged in stablecoins, and to which exchanges opened USDC withdrawals in the mainnet launch week.
Who signs the blocks
Circle announced a founding validator cohort of eleven organisations, rolled out in phases: BlackRock, DTCC, Galaxy, ICE, Mastercard, MoneyGram, SBI Group, Standard Chartered, Sumitomo, Visa and Worldpay (Global Payments). In the same materials Arc is called an "open L1 blockchain" with a "permissioned validator set" of regulated institutions: anyone can send a transaction, while only members of that set confirm blocks. Circle is exploring a transition to proof-of-stake in 2027.
Sources and check date
- Circle pressroom — Arc mainnet launch, 16 September 2026 — the ARC token mint, validators, launch exchanges and wallets.
- Circle Form 8-K, 11 May 2026 — the ARC sale to institutional investors and its terms.
- Circle Form 10-Q, second quarter of 2026 — the ARC sale total after the second closing.
- explorer.arc.io block explorer — the official mainnet block explorer.
- Arc documentation — connecting to the network — chain ID, RPC, gas currency.
- Arc blog — mainnet goes live on 16 September 2026 — status, fee model, finality, stated audience.
- Circle pressroom — founding validator cohort and integrations for Arc — validators, wallets, exchanges, custody, DeFi, payments.
- ARC token whitepaper — token description and status.
- Uniswap deployment list — support for the chain with its own addresses.
Checked on 17 September 2026. Contract addresses and network parameters were verified by querying the chain, and the venues’ mechanics against their own documents.