#ARU Overview

ARU (Acua Reserve Unit) is an ERC-20 token backed 1:1 by allocated gold held in regulated custody. APs (Authorized Participants) mint ARU by depositing USDC and redeem ARU for USDC at NAV. ARU itself trades freely on-chain and is used by downstream DeFi protocols as a gold-backed building block.

#The promise

• 100% backed. Every ARU in circulation corresponds to gold of equivalent NAV held in treasury or liquid USDC pending gold conversion.
• AP-restricted primary market. Only allowlisted APs can mint or redeem. This is how the protocol keeps KYC and AML obligations satisfied.
• Permissionless secondary market. Anyone can hold, send, or receive ARU. No transfer restrictions, no blocklist, no pause on transfers.
• Transparent settlement. Every mint and redemption records the AP-agreed price bound on-chain. All settlements happen within those bounds or funds are automatically returned.
• Independently audited. The production contracts were reviewed by Nethermind Security (report NM-0902, June 2026) with zero findings. Read the report.

#High-level flow

Mint:     AP sends USDC  →  request held in contract  →  multisig approves  →  ARU minted, USDC to treasury
Redeem:   AP sends ARU   →  request held in contract  →  multisig approves  →  ARU burned, USDC to AP

Both flows are per-request, not epoch-batched. Typical settlement is under 4 hours; maximum is 48 hours, after which the request automatically expires and funds are returned.

#Key properties for APs

• You set the price bound. On every request, you specify the worst price you'll accept (highest USDC-per-ARU on mint, lowest on redeem). The multisig cannot settle outside your bound. This is your consent on-chain.
• You can cancel any time before approval. If you submit a request and change your mind — market moved, typo, whatever — you cancel and your funds come back. No waiting, no admin cooperation needed.
• If the multisig never approves, you (or anyone) reclaims your funds after 48h. Expiry is permissionless. Your funds never get stuck waiting on administrative action.
• Pending mint USDC lives in the contract, not the treasury. It can't be converted to gold until your mint is approved. This is what makes the refund guarantee work.

#Key properties for integrators

• Standard ERC-20 + EIP-2612 Permit. No transfer hooks, no fee-on-transfer, no rebasing, no blocklist.
• Chainlink-compatible price feed. ARUPriceOracle implements AggregatorV3Interface. Use latestRoundDataStrict() if you want hard-fail on stale data, or latestRoundData() for drop-in Chainlink compatibility.
• No proxy, no upgrade path. The ARU token and all manager contracts are immutable. What deploys is what runs forever.

#What to read next

If you're becoming an AP: Becoming an AP and Subscribing.

If you're integrating ARU as a price feed or reserve asset: Contracts & Addresses.

If you want to understand the full trust model and safeguards: Safeguards.

For the independent security review: Audit History or the raw report — Nethermind NM-0902 (PDF, 0 findings).

For engineering-level detail (threat model, deployment ceremony, auto-signer design, audit history), see the Engineering section.