Onramp Kit embeds a hosted purchase widget that delivers $USDC or $EURC to a specified Arc wallet. Debit cards, Apple Pay and Google Pay are supported in the U.S., UK and select EU countries, among other jurisdictions. Bank transfers support $USDC in select U.S. states and EU countries; credit cards are not supported.
Integrators need a Circle API key and must complete business verification to enable card and mobile-wallet payments. Users must be at least 18 and meet local age-of-majority requirements, pass the provider’s identity and sanctions checks, and qualify under its geographic restrictions.
Arc’s onramp terms identify Transak as the provider processing card, Apple Pay and Google Pay purchases. BVNK and Lead Bank provide virtual-account and payment-processing infrastructure, while Socure verifies identity information on behalf of payment processors. Circle does not provide those services itself. The kit does not yet offer conversion back to fiat.
Earn Kit lets apps offer $USDC and $EURC deposits into lending vaults. Depositors receive vault shares representing their position, and integrators choose which vaults to offer rather than connecting separately to each vault contract. Arc says the initial Morpho offering includes vaults lending into markets backed by ETH and BTC collateral.
The SDK supports deposits, position tracking and withdrawals. Deposited funds sit in vault contracts, not with the software provider, and lending positions can lose value.
Borrow Kit uses cirBTC collateral—not native bitcoin—to obtain $USDC. Its flow combines posting collateral and borrowing in one transaction on Arc, with repayment releasing the collateral. Apps can subscribe to updates when a loan’s health changes.
That monitoring does not remove liquidation risk. Arc’s loan-health documentation says liquidation takes place directly through the underlying protocol, outside the SDK: once a position breaches its market’s threshold, a liquidator can repay debt in exchange for collateral at a discount.
The bigger picture
A Vault Sentinel Is Not a Liquidity Backstop
Arc’s ‘Circle-guarded’ designation illustrates a distinction in DeFi risk control: an institution can supervise a vault without managing its portfolio or guaranteeing its assets. Circle describes a limited sentinel role, not vault ownership, strategy control or a guarantee against losses.
Morpho’s Vault V2 design separates curators who set risk boundaries, allocators who deploy liquidity and sentinels who intervene. But permission to withdraw is not the same as available liquidity: Morpho’s sentinel guide says to repeat deallocation as liquidity becomes available in an illiquid market. Veto and cap-reduction powers can constrain risk-taking; they are not a promise of cash on demand.
