> ## Documentation Index
> Fetch the complete documentation index at: https://docs.arc.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Stablecoin native model

> Arc is built around stablecoins as first-class assets, with USDC as the native gas token, EURC for euro-denominated transfers, and USYC for yield-bearing use cases.

Arc is purpose-built around stablecoins. USDC is the native gas token, so
transaction fees are denominated in dollars rather than a volatile asset. EURC
and USYC are natively supported alongside USDC, giving applications access to
multi-currency payments and onchain yield without bridging or wrapping. There is
no volatile native token on Arc.

## USDC as the native gas token

On most EVM blockchains, a volatile token (such as ETH) serves as the native
asset for gas fees and value transfer. Arc replaces this with USDC. Every
transaction fee, balance, and native transfer on Arc is denominated in USDC.

This means:

* Fees are predictable in dollar terms.
* You hold a single asset for both gas and application-level transfers.
* There is no need to acquire or manage a separate volatile token.

### Two interfaces, one balance

USDC on Arc has two interfaces that share the same underlying balance:

| Interface  | Decimals | Purpose                                                |
| :--------- | :------- | :----------------------------------------------------- |
| **Native** | 18       | Gas accounting, native sends, and `msg.value`          |
| **ERC-20** | 6        | application-level transfers, approvals, and allowances |

The native representation uses 18 decimals, consistent with how ETH works on
Ethereum. The ERC-20 interface at
[`0x3600000000000000000000000000000000000000`](/arc/references/contract-addresses#usdc)
uses 6 decimals to match the standard USDC representation on other EVM networks.

<Info>
  The ERC-20 and native interfaces share the same underlying balance. An ERC-20
  transfer directly moves the native balance, and a native send is reflected in
  the ERC-20 balance. These are not two separate tokens. For the complete
  protocol reference, see [EVM differences](/arc/references/evm-differences).
</Info>

Because the two interfaces represent one asset, Arc behaves differently from
other EVM chains in ways that can break common assumptions:

* `USDC.balanceOf(addr)` and `addr.balance` represent the same value in
  different decimals (6 vs 18). A `balanceOf` of `0` does not mean the native
  balance is `0`; amounts below 1×10⁻⁶ USDC are truncated in the ERC-20 view.
* Native transfers into or out of a contract also change its ERC-20 USDC
  balance.
* A native transfer can revert even with a sufficient balance (for example,
  because of the blocklist or zero-address rules).

<Warning>
  If you are porting an existing contract, review the [Porting contracts to Arc
  checklist](/arc/tutorials/porting-contracts-to-arc) for the dual-interface
  edge cases, and see the [value transfer
  rules](/arc/references/evm-differences#value-transfer-rules) for the full set
  of restrictions.
</Warning>

Every USDC movement (native sends and ERC-20 transfers alike) emits a standard
ERC-20 `Transfer` log from a system address, Arc's implementation of
[EIP-7708](https://eips.ethereum.org/EIPS/eip-7708) (an Amsterdam-track Ethereum
proposal). Because this system event covers all USDC movements at 18-decimal
precision, it gives wallets and indexers a single universal source of truth for
balance changes.

For fee parameters and gas pricing details, see
[Gas and fees](/arc/references/gas-and-fees). For the rationale behind stable
fee denomination, see [Stable fee design](/arc/concepts/stable-fee-design).

### Indexing USDC movements

The native system emitter logs a `Transfer` (18 decimals) for every USDC
movement, so indexing it alone gives complete coverage. The ERC-20 USDC contract
additionally logs its own `Transfer` (6 decimals) for ERC-20-interface activity,
so a single ERC-20 transfer emits both; match on the emitter address to avoid
double-counting. For the full event reference, including emitter addresses, the
mint and burn mapping, and legacy native events, see
[USDC system events](/arc/references/usdc-system-events). For a step-by-step
walkthrough, see [Index Arc events](/integrate/infrastructure/indexing-events).

## Natively supported stablecoins

Beyond USDC, Arc natively supports additional stablecoin assets at the protocol
level, meaning they are deployed as pre-configured contracts at genesis, not
bridged or wrapped from other blockchains.

### EURC

EURC is Circle's euro-denominated stablecoin. It is deployed as a standard
ERC-20 token on Arc with 6 decimals, enabling euro-denominated payments, FX
workflows, and multi-currency applications without relying on third-party
bridges. For the EURC contract address, see
[Contract addresses](/arc/references/contract-addresses#eurc).

### USYC

USYC is a yield-bearing token representing shares of a tokenized money market
fund, a regulated investment vehicle that holds short-duration U.S. Treasury
securities and distributes yield to token holders. It provides onchain access to
regulated, low-risk yield for institutional participants.

USYC is only accessible to institutions outside the United States, subject to
eligibility restrictions and a \$100,000 USD minimum investment.

For token addresses and testnet faucet instructions, see
[Contract addresses](/arc/references/contract-addresses).

## Design rationale

Arc's stablecoin-native model is a deliberate architectural choice, not a
compatibility layer added after launch. Three principles guided the design.

### No volatile native token

Traditional blockchains require users to hold a volatile native token to pay
fees. This creates friction for financial applications: users must acquire the
token, manage price exposure, and convert between the fee token and the assets
they actually want to use. Arc eliminates this by making USDC the native token
from day one.

### Single gas denomination at launch

Arc launches with USDC as the sole gas token rather than supporting multi-token
gas payments from the start. A single denomination simplifies the fee market,
avoids oracle dependencies for gas price conversion, and keeps the protocol's
economic model straightforward. Multi-stablecoin gas payment through paymasters
(smart contracts that sponsor or redirect gas fees on behalf of a user) is not
supported at launch.

### Stablecoins as first-class primitives

USDC, EURC, and USYC are not tokens added after launch. They are integrated at
the protocol level, which means applications can compose across stable assets
with consistent interfaces and without external dependencies. This positions Arc
as infrastructure specifically designed for payments, lending, FX, and treasury
management.