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In development · Simulation live

Payments are final.
Mistakes shouldn’t be.

UNDO is buyer protection for USDC payments on Arc. Sellers post a bond and get paid instantly. If a seller loses a dispute, the refund comes out of the bond.

Try the simulationRead the docs

CtrlZfor USDC payments.In development. Simulation only.

UNDO logo: a round whorl of soft blue stems with a glowing cream centre

The problem

On Arc a payment settles in under a second. Then it is over.

Finality is what makes USDC useful. It also means buyers and AI agents have no recourse when something goes wrong.

Cards have chargebacks. USDC has nothing.

How it works

The money moves. The guarantee stays.

A bond stands behind every payment, so the seller does not have to wait and the buyer does not have to trust.

Buyerpays 180.00UndoPayfee 0.90Sellercapacity 5,000Bond1,000 USDCExample amounts in USDC

Two lanes

One protocol for people and for agents.

Commerce disputes need judgement. Agent disputes mostly need proof. UNDO treats them differently.

Comparison of the Commerce lane and the Agent lane
PropertyCommerce laneAgent lane
PayerA person or a business buying from a seller.An AI agent paying per request over x402 or nanopayments.
What is protectedOne purchase of goods or services, up to 2,500 USDC per payment.A session with a spending cap. Every paid API response must carry a receipt signed by the seller.
Refund window7, 14 or 30 days, chosen by the seller.From 10 minutes to 24 hours.
Typical disputeThe package never ships, or the item is not what was sold.The API is down but keeps charging. Responses arrive late or without a receipt.
ResolutionThe seller has 48h to refund or contest. No answer, the buyer wins. Otherwise 3 arbitrators vote within 72h, with one appeal to 7.A missing or late signed receipt is refunded automatically. No arbitration needed.

Read more about the Commerce lane and the Agent lane.

Who it is for

Three sides of the same payment.

For sellers

Be paid now, not in 14 days.

  • Instant payout while open exposure stays under bond × leverage.
  • A flat 0.5% fee, or 0.35% with $UNDO staking. No fee on the bond.
  • Idle bonds earn USDC yield on Arc lending markets. You keep 90% of it.
  • A public profile that buyers and agents can read before they pay.

Lea sells ceramicsExample

Bond posted
1,000.00
Leverage after day 30
5x
Capacity
5,000.00
Sale, paid instantly
180.00
Fee at 0.5%
0.90

Her open exposure rises by 180 USDC until the refund window ends. Amounts in USDC.

For buyers

A refund window on a final payment.

  • An Undo button for 7, 14 or 30 days, depending on the seller.
  • Protection costs you nothing. The seller pays the fee.
  • To dispute, deposit 2% (minimum 1 USDC). You get it back if you win.
  • If the seller stays silent for 48h, you win.

Sam’s vase never shipsExample

Payment
180.00
Dispute deposit at 2%
3.60
Seller answer within 48h
none
Refund from the bond
180.00
Deposit returned
3.60

No arbitration was needed. Silence is a loss for the seller. Amounts in USDC.

For agents

Stop paying for responses you never got.

  • Open a protected session with a spending cap.
  • Each paid API response carries a receipt signed by the seller.
  • A missing or late receipt is refunded automatically.
  • Seller profiles are machine-readable, so an agent can check before it pays.

A monitoring agentExample

Session cap
5.00
Price per call
0.02
Calls paid without a receipt
212
Refunded automatically
4.24
Arbitrators involved
0

The API went down mid-session. The claim is pure arithmetic: 212 × 0.02. Amounts in USDC.

Simulation

Try it before it exists.

The simulator runs the protocol’s formulas with demo numbers. Be the seller, the buyer or the agent. No transaction, no signature, no approval.

Live preview Demo data

Leverage tier
Capacity
5,000.00
Open exposure
620.00
Free capacity
4,380.00

Instant payoutfee 0.90

Exposure stays under bond × leverage, so the seller is paid at once.

Open the full simulator

$UNDO

Not launched yet

The token is not live. It will be soon.

$UNDO has not launched. There is no contract address yet. Any token using this name today is not ours.

The launch and the official contract address will be announced only on X at x.com/UndoOnArc.

Follow @UndoOnArc for the launch(opens in a new tab)About $UNDO

What $UNDO will do

  • Staking to arbitrate

    Stake $UNDO to be eligible for the random draw that picks arbitrators for a dispute.

  • Slashing

    Arbitrators who vote with the minority, or who do not show up, are slashed.

  • First-loss layer

    In phase 2, staked $UNDO absorbs losses ahead of Guarantee Pool depositors.

  • Fee discount for sellers

    Sellers who stake pay 0.35% instead of 0.5% on each protected payment.

  • Bounded governance

    Stakers vote on parameters only. Governance never has power over funds.

Where the 0.5% fee goes

paid by the seller, in USDC or EURC

50%Arbitrators

Paid for resolving disputes

30%Guarantee Pool / treasury

Third layer of the refund waterfall, phase 2

20%Buyback to stakers

Market buyback, sent to $UNDO stakers

Supply Planned
1,000,000,000
Fixed
Launch Planned
Fair launch
Planned
Presale Planned
None
No presale

You will never need $UNDO to pay or to get paid. Payments, bonds and fees stay in USDC and EURC.

Roadmap

Four phases over 90 days.

Phases, not dates. Each one ships when it is ready and reviewed.

  1. Phase 1Now

    Site, docs, simulation

    • This website
    • Full documentation
    • The interactive simulator

  2. Phase 2

    Testnet

    • Contracts on Arc Testnet
    • x402 receipt middleware
    • First audit

  3. Phase 3

    Capped mainnet

    • Mainnet with strict caps
    • Agent lane first
    • Commerce lane follows

  4. Phase 4

    Open arbitration

    • Open arbitration and appeal
    • Second audit
    • Legal review of the Guarantee Pool

FAQ

Straight answers.

Is it live?

No. UNDO is in development. There are no deployed contracts and no real payments. What you can use today is the simulation and the documentation.

Do funds move in the simulation?

No. The simulation never sends a transaction and never asks for a signature or an approval. If you connect a wallet, it is used as an identity and to read your USDC balance on Arc. Every amount in the simulator is demo data stored in your browser.

Who arbitrates?

If a seller contests a dispute, 3 arbitrators are drawn at random among $UNDO stakers. They vote by commit-reveal within 72 hours. There is one appeal, to 7 arbitrators, with a doubled deposit. Arbitrators who vote with the minority are slashed. In the Agent lane most cases need no arbitrator: a missing or late signed receipt is refunded automatically.

What if the seller disappears?

A seller has 48 hours to refund or contest. No answer means the buyer wins. The refund comes from the seller’s escrowed balance first, then from the seller’s bond. The bond stays in place while payments are still inside their refund window. The money moves, the guarantee stays.

What does it cost?

The seller pays 0.5% of each protected payment, or 0.35% with $UNDO staking. Buyers pay nothing to be protected. To open a dispute, a buyer deposits 2% of the amount (minimum 1 USDC), returned if they win. Gas on Arc is paid in USDC.

Which wallets work?

Any wallet that announces itself in the browser through EIP-6963, including MetaMask, Rabby, Coinbase Wallet and Rainbow. WalletConnect appears when the deployment has it configured. The simulation also works without a wallet, with a generated demo identity.

Is UNDO affiliated with Circle?

No. UNDO is an independent project built on Arc. Its design extends the Refund Protocol, which Circle Research published as open source under Apache 2.0. That is a licence anyone can use. It is not a partnership or an endorsement.

When is the token?

$UNDO has not launched and there is no contract address yet. Any token using this name today is not ours. The launch and the official contract address will be announced only on X, at x.com/UndoOnArc.