Across

Across is an intent-based bridge and cross-chain swap product. Instead of making a recipient wait for a deposit to complete the full settlement journey, a user states the desired destination asset and a relayer can supply it from its own capital while the protocol settles the accounting later.

One intent can bridge, swap, and continue on the destination

An Across order names the origin and destination chains, input amount and asset, recipient, and, for a swap, the desired output asset and minimum amount. The input is escrowed through the origin SpokePool. A relayer that claims the order sends the requested output on the destination chain, so a cross-chain swap need not first leave the recipient with an intermediate bridged token.

Supported orders can include a destination action after the fill, such as supplying the received funds to another protocol. The current RFQ system uses fixed fees and relayers compete on fill speed, while the quoted route determines which chain, token pair, amount and action are actually available.

Relayers front the fill; the HubPool settles later

Relayers are permissionless and choose the chain where they want reimbursement. That lets them manage capital across the network rather than holding identical inventory on both sides of every route. Passive liquidity in the Ethereum HubPool supports the interval between a fast destination fill and reimbursement.

An off-chain Dataworker groups fills into a merkleized bundle and proposes it to the HubPool with a bond. The UMA Optimistic Oracle gives the bundle a challenge period; after finalization, refunds are sent to relayers' chosen repayment chains and canonical bridges rebalance HubPool and SpokePool funds. The fast fill and the slower liquidity settlement are deliberately different stages.

Quoted routes, not universal chain coverage

Across has a HubPool on Ethereum and SpokePools on supported chains, but a deployed chain does not make every token pair or direction transferable. The current quote determines whether the chosen origin, destination, assets, amount and destination action can be filled. ERC-20 inputs can also need a SpokePool allowance before the main transaction.

This makes Across a focused transfer and swap system, not a general-purpose route for arbitrary contract messages. A fast delivery still depends on a relayer being willing and able to fund that particular intent, while reimbursement follows the later optimistic bundle process.

Canonical routes, pooled liquidity, and intent fills

A chain's canonical bridge is the natural alternative when its native or canonical asset representation is the priority. Across instead offers a quoted outcome, including supported cross-chain swaps and follow-on actions, by putting relayer capital in front of later settlement.

Stargate uses unified cross-chain liquidity pools and LayerZero messaging for supported transfers. Across uses competitive relayer fills, HubPool accounting and later canonical rebalancing. LayerZero itself sits lower in the stack: it is for teams building their own cross-chain application, while Across supplies the completed intent and settlement route.