Sell a pending Arbitrum withdrawal now instead of waiting 6.4 days. Exit Market proves it is real and unclaimed on-chain, against the rollup's own commitments. No oracle, no committee.
Exit Market: sell a pending Arbitrum withdrawal instantly, proven on-chain.
Leaving Arbitrum through the canonical bridge, the only exit that needs no trust beyond the rollup, takes 6.4 days, and once a withdrawal has started nothing can speed it up. In 30 days, $51M of tokens left Arbitrum One this way. On one day, $10.2M sat in the challenge window, and $5.06M of exits finished the wait but were never claimed. Fast bridges have to be chosen before you withdraw, and they skip most Orbit chains: Across supports none of Xai, ApeChain, RARI, Sanko or EDU Chain.
Every Arbitrum token gateway has a hook, transferExitAndCall, that lets the owner of a pending withdrawal hand it to someone else. On mainnet it had never been used, because the gateway cannot tell a real withdrawal from a fake one, so nobody could safely buy one. Exit Market is the missing check. It proves on-chain, against the rollup's own commitments, that a withdrawal is real and unclaimed, then in one signature:
sells it now to an ERC-4626 vault, paid in USDG;
or lists it at your price for any wallet to buy;
or, gasless: withdraw to the router and sign one order; a relayer settles it, so you need no ETH on the other side.
The buyer becomes the exit's owner, and the Outbox pays them face value when the window ends.
Proof, not trust. The market rebuilds the withdrawal's Outbox leaf byte for byte, checks its Merkle path against the send root a pending rollup node committed, and checks the Outbox slot is unspent. No oracle, no committee.
A disputed node stops trading. The verifier walks the pending chain back to the latest confirmed node and refuses any root with a rival node at any level.
No admin. The live market renounced ownership after allowing the gateways: nobody can add a gateway, change the fee or move funds.
Buyers consent, and the relayer cannot steal. The vault must return a consent value before it is charged, and the signed order fixes the buyer and the minimum proceeds.
Sellers get their money now. Liquidity providers earn the discount (0.10% plus 10% APR on the time left, about 15.7% APR at full use), and the market takes 0.25%. It runs on the bridge Orbit chains already have, with no upgrade or opt-in, and a BOLD verifier, proven on an Arbitrum One mainnet fork, extends it to Arbitrum One itself.
USDG is the money on every side of the trade: the vault is an ERC-4626 USDG vault, sellers are paid in USDG, listings are priced in USDG, and liquidity providers earn their yield in USDG. The live demo withdraws USDG from Xai Testnet, and the site's faucet hands out test USDG so anyone can try it.
Live app · Code · Demo video
Exit Market was built from scratch during the hackathon, solo, end to end.
ExitMarket: verifies an exit inside the gateway's own hook, then sells it or lists it (list, buy, cancel, settle).
ExitVault: ERC-4626 USDG vault that prices exits by time to confirmation, values each at cost plus the accrued discount, and writes off exits from rejected nodes.
ExitIntentRouter: gasless sign-once exits (EIP-712), with reclaim and recovery.
LegacyRootVerifier (pending nodes, rival check) and BoldRootVerifier (BOLD assertions).
440 tests (unit, fuzz including a brute-force model of rollup node trees, stateful invariants, exploit regressions) plus 10 fork tests against the real Xai and Arbitrum One contracts; 99.42% line coverage; every Slither finding triaged; six internal review rounds (AI-assisted, not a third-party audit).
The Outbox item and its Merkle path rebuilt on-chain, with proofs from NodeInterface.constructOutboxProof.
Legacy nodes: confirmData = keccak256(blockHash, sendRoot), and a walk to the latest confirmed node.
BOLD: assertion preimages registered once, every pending ancestor checked. On an Ethereum mainnet fork, a real pending Arbitrum One withdrawal was proven under a 134-deep real pending chain and listed through the real L1 gateway.
Withdraw to the router and sign one order; the site's relayer settles it. A wallet holding 0 ETH on Arbitrum Sepolia sold its exit this way.
A permissionless keeper executes each exit once its window ends and collects it for the vault. It runs around the clock on GitHub Actions.
A viem library shared by the app, scripts, relayer and keeper: legacy and BOLD proof builders, hook encoding, listings, the relayer, the keeper's decision table.
The proof core ported to Rust with Stylus, deployed and checked on-chain against a real Xai send root.
Next.js app: a landing page; a desk (sell now, list at your price, gasless fast exit, test funds, the vault); a live Exit Explorer of every Xai Testnet withdrawal; a pitch deck.
Every step is a real transaction: exits sold while pending, a listing bought by a second wallet, a gasless exit from a wallet with 0 ETH, and the keeper paying them out.
Deployed on Arbitrum Sepolia with Xai Testnet (Orbit L3). Contracts verified on Sourcify.
No external funding raised to date. Exit Market is a solo, self-funded project built for this buildathon.
Next step: an independent security audit and a mainnet launch on Orbit chains. Open to ecosystem grants and investor conversations to fund it.