Integrating Arc for Deposits and Withdrawals

For exchanges building on Arc, the important thing about Arc is not just that it is EVM-compatible. It is that USDC is Arc’s native asset.

On Arc, exchanges support one unified USDC asset for transfers and fees, without a separate gas-token balance to manage. Deposits can be credited after final inclusion, and withdrawals draw fees from the same asset being moved. The main exchange work is making sure indexing, accounting, and withdrawal logic reflect that model.

Arc is EVM-compatible, so address generation, signing, and transaction broadcasting follow familiar patterns. The operational work starts where Arc differs: USDC is the native gas asset, deposits surface through a unified Transfer event, and finality is deterministic after a single block.

What Arc changes for exchange operations

Three Arc design choices affect every exchange integration:

• USDC is the native gas asset
• native and ERC-20 USDC share one underlying balance
• transactions are final after one block confirmation

For exchange teams, those choices show up in a few clear ways:

• hot wallets do not need a separate gas-token float
• deposit monitoring should follow Arc's unified Transfer event model
• accounting systems should normalize units before comparing values
• confirmation policy can be simpler because single-block inclusion is final

Step 1: Start with the one-asset model

On Arc, native USDC and ERC-20 USDC are not two assets. They are two interfaces to one underlying balance. The native side uses 18 decimals. The ERC-20 side uses 6 decimals. Both point to the same funds.

This is important to understand because exchanges often split operational responsibilities across multiple systems:

• deposit monitors
• reconciliation jobs
• customer ledger services
• treasury dashboards
• withdrawal workers

If one part of the stack treats native and ERC-20 USDC as separate holdings, the exchange can end up with missed credits, duplicate accounting, or confusing customer balances.

For most exchanges, the cleanest approach is to keep customer balances, credits, and internal ledger accounting in 6-decimal ERC-20 USDC units, while understanding that the underlying balance is shared with the native side. That gives the exchange one consistent unit for deposits, withdrawals, and reconciliation, while native precision still needs to be handled when operations compare against native balances directly.

Step 2: Detect deposits through Arc’s unified Transfer event

On Arc, exchanges should monitor the native USDC Transfer event from the system emitter. That event covers plain native sends and the native leg of ERC-20 transfers, which is why it is the right source for deposit detection.

For exchange operations, that leads to one strong rule:

• use the unified Transfer event to detect deposits
• do not combine that with separate balance-based crediting logic for the same address

The common failure mode is double-crediting. If a system watches Transfer events and also treats eth_getBalance changes as new deposits, it can count one deposit twice.

For exchanges, the key is to keep deposit detection and crediting consistent. One deposit should have one detection path, one crediting rule, and one way to prevent duplicate credits during retries or replays.

Step 3: Normalize decimals before reconciling anything

Arc uses two unit systems, and they appear in different places:

• native USDC Transfer event values use 18 decimals
• ERC-20 Transfer event values use 6 decimals
• native balance reads use 18 decimals
• native value fields in transactions use 18 decimals

That means reconciliation systems should not compare raw event values, raw native balances, and raw transaction fields directly.

This affects:

• deposit crediting
• balance reconciliation
• hot wallet monitoring
• treasury reporting
• exception handling
• withdrawal construction

If an exchange keeps customer accounting in 6-decimal USDC units, native 18-decimal values should be converted before they are compared to ledger entries or credited balances. 

This is another place where pre-launch testing matters. A decimal mismatch might later show up as a reconciliation issue, a confusing balance display, or an operations exception.

Step 4: Handle withdrawals with Arc's gas model in mind

Arc also changes withdrawal operations in a useful way: the hot wallet pays both the transfer amount and the gas fee in USDC.

The operational pattern is familiar, but the assumptions are different:

• validate destination addresses as standard EIP-55 Ethereum addresses
• check the blocklist before sending
• estimate gas before broadcast
• confirm the transaction after one included block

For most exchanges, native USDC transfers will be the default withdrawal path. They may have different fee characteristics than an ERC-20 transfer() call, they work with any address, and they still show up in the same transfer history model. ERC-20 transfer() is still available when a team specifically wants ERC-20 call semantics or prefers to work directly in 6-decimal amounts.

That means the withdrawal worker should understand both unit systems:

• customer-facing withdrawal amounts are usually tracked in 6-decimal USDC
• native transaction value fields must be encoded in 18-decimal units

Before launch, exchanges should test the conversion from 6-decimal withdrawal amounts to 18-decimal native transaction values. They should also test blocklist handling and destination validation, because both can affect whether a withdrawal succeeds.

Step 5: Align confirmation and ordering policy with Arc finality

On Arc, deposits and withdrawals use Arc’s deterministic finality model. Exchanges should set crediting and completion timing based on current Arc documentation and their own risk controls. This may allow shorter confirmation windows than on some networks.

That should simplify:

• deposit credit timing
• withdrawal completion logic
• operational alert thresholds
• customer-facing status updates

Exchange systems should also be careful with ordering logic. For ordering-sensitive workflows, block number is the safer primitive. For most teams, this is the right place to review confirmation policy as well. Arc removes the need for long confirmation windows, but the exchange still needs internal systems to reflect that model consistently.

The exchange opportunity on Arc

Arc may simplify certain exchange operations in ways users notice immediately. Deposits can be credited after one block. Hot wallets do not need a separate gas token. Users move the same asset they already care about.

Exchanges still need the right indexing model, unit conversions, and withdrawal assumptions. Once those pieces are in place, Arc becomes easier to support cleanly: one USDC asset, one confirmation policy, and one less token for users and operations teams to manage.

For teams moving into implementation, the next step is to work through Arc's exchange integration guides for deposits, withdrawals, CCTP liquidity movement, and custody configuration. 

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