Circle Internet Group said Arc public mainnet is live, opening a new Layer-1 blockchain that uses USDC as native gas and is secured at launch by a permissioned set of institutional validators.
The company describes Arc as an “Economic OS for the internet,” an open platform for markets, real-time value movement, tokenized assets, and agentic economic activity. Official network documentation lists the public mainnet chain ID as 5042, with USDC as the gas token and developer access described as permissionless even while validator participation remains permissioned.
Circle first introduced Arc on August 12, 2025, as an EVM-compatible Layer-1 purpose-built for stablecoin finance. The public testnet followed on October 28, 2025. A founding validator cohort was named on August 5, 2026, ahead of today’s public opening.
“Arc is built on a simple premise: that the global financial system deserves a blockchain network it can trust,” Circle co-founder, chief executive and chairman Jeremy Allaire said in that August announcement. He said more than 100 ecosystem and enterprise builders were already active on private mainnet.
A year-long path from announcement to public rails
Circle’s original August 2025 post framed Arc as a response to limits associated with general-purpose chains: volatile gas tokens, probabilistic finality, and public-by-default transfers. The company said the network would use USDC as native gas, deliver deterministic sub-second finality through a consensus engine called Malachite, support a built-in foreign-exchange design, and later offer opt-in privacy.
The October 2025 public testnet launch opened that design to developers and enterprises. Circle said more than 100 companies across payments, markets, custody, and onchain applications were participating. Allaire said those firms “reach billions of users” and operate across Africa, the Americas, Asia, Europe, and the Middle East.
Circle later placed Arc inside a broader infrastructure thesis. In its 2026 Internet Financial System report, the company described three layers: regulated digital assets such as USDC, EURC, and USYC; Arc as settlement infrastructure; and applications including the Circle Payments Network. The same report said Arc’s testnet had drawn more than 100 participating companies.
The company has not presented the chain as a replacement for every existing network. Official materials say Arc is intended to complement other blockchains where USDC already circulates, with CCTP and Gateway used for cross-chain movement.
How the chain is designed to work
According to Arc documentation, the network separates consensus and execution. Consensus runs on Malachite, a Byzantine fault-tolerant engine in the Tendermint family. Execution uses an EVM environment so Solidity contracts and common Ethereum tooling can be reused. Official materials describe deterministic, sub-second finality and say committed blocks are not subject to reorganization.
The fee model is the most distinctive design choice. Circle’s gas explainer says every transaction fee is paid in USDC rather than a separate volatile token. The company says the fee market is inspired by Ethereum’s EIP-1559 design but smoothed so short bursts of demand do not produce sharp swings. Official docs also describe a dual interface for USDC: an 18-decimal native view used for gas and a 6-decimal ERC-20 view used by applications.
Validation is not open at launch. Circle said Arc is operated by a permissioned Proof-of-Authority set. Named founding validators, alongside Circle, include BlackRock, DTCC, Galaxy, Global Payments, ICE, Mastercard, MoneyGram, SBI, Standard Chartered, Sumitomo Corporation, and Visa.
Official releases present that roster as an attempt to meet institutional operational and compliance expectations. The same materials note that Arc has not been reviewed or approved by the New York State Department of Financial Services or any other regulator, and that use of the network involves ordinary blockchain risks.
Circle has published an Arc litepaper describing the chain as a settlement layer for payments, FX, and capital markets. Roadmap items listed in official posts include opt-in privacy and a later move from Proof of Authority toward Proof of Stake.
Markets, assets, and an unlaunched network token
Circle’s mainnet blog says assets, markets, and applications are available from the first block. Named components include Arc Portal, Arc Studio, App Kits, and Circle Agent Stack.
The company said lending and borrowing venues include Aave and Morpho, and that StableFX is available on Arc for 24/7 onchain foreign exchange among fully reserved stablecoins.
Tokenized products listed as live for eligible users include BlackRock’s BUIDL, Circle’s USYC, Janus Henderson’s JAAA and JTRSY, and cirBTC, Circle’s programmable Bitcoin product. Circle also listed banks, exchanges, wallets, custody firms, and payment companies as building or connecting to the network. DTCC has said it is collaborating on tokenization of DTC-custodied assets on Arc beginning in the second half of 2027, according to Circle’s validator announcement.
Circle said it completed a genesis mint this week of 10 billion ARC tokens in the United States. Official language is carefully limited. The company said the mint is a technical milestone, not a commitment to a public token launch, and that network fees remain payable in USDC. It also said discussion of ARC utility is exploratory and that no decision has been made on development, deployment, or public distribution. Circle added that it is exploring a possible transition toward Proof of Stake in 2027.
Whether institutions treat Arc as core settlement infrastructure will depend on usage after launch, not on the partner list published at genesis. For now, Circle has opened a public chain with dollar-denominated fees, institutional block producers, and a stack of financial applications already wired to USDC. The test of the “Economic OS” claim begins with whether those rails carry real volume.
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