Wait or switch chains: when do relayers fill?

Relayers can pay you on the destination chain before your transfer looks complete. They do this after they detect your source-chain deposit, using their own funds.

That can feel odd if you are used to an exchange. An exchange usually waits for a deposit, credits your account, then lets you trade. With a cross-chain bridge, a relayer can send your destination tokens while the original deposit is still settling or showing as pending in the app.

What does a relayer see before you see the deposit?

A relayer acts after your deposit transaction is recorded on the source chain. Your wallet sends tokens to a bridge contract and includes instructions: the destination chain, token, recipient, amount, and fee. The contract records those instructions onchain, meaning in the blockchain’s shared transaction record.

Relayers watch for that record. Once they detect it, they check that the request is valid, has not expired, and can be filled under its rules. Keep the chain and token choices exact because how acrossbridge routes transfers depends on the route you select.

Then the relayer sends the promised destination tokens from its own balance. Think of it like a shopkeeper handing you a replacement item after checking a courier’s pickup record, before the courier’s parcel reaches the warehouse. The relayer is advancing its own funds while the bridge process catches up.

Why can the destination arrive before the app updates?

The source deposit and destination payment happen on separate blockchains. Each has its own transaction record, and your wallet or bridge app may take time to display updates from both. So your destination balance can change while the bridge screen still says “pending.”

“Before the deposit appears” does not mean the relayer pays before you send anything. The source transaction must first be visible to the relayer onchain. The apparent lead comes from the difference between a recorded deposit, a relayer’s quick payment, and the time your app takes to show each event.

On acrossbridge, check the source transaction in your wallet and the destination balance separately. A destination payment means the relayer has filled your request; it does not mean the relayer has already been repaid. If the source transaction fails or the request expires without a fill, check the bridge’s status and refund instructions before trying again.

What does the relayer pay, and what happens next?

The relayer advances the destination amount set by your request, then waits to recover its money through the protocol’s settlement process. Settlement means recording valid fills and paying relayers back from pooled funds. Across batches this accounting, and UMA’s Optimistic Oracle helps check disputed settlement claims. An optimistic oracle accepts a claim unless someone challenges it with evidence.

Your quote shows the amount you should receive and the fees deducted from your transfer. The total cost can include the relayer’s fee, a liquidity-provider fee for pooled funds, and gas for your source transaction. Gas is the network fee for processing a transaction. Check the quoted receive amount before signing; fees and available routes can change.

I would judge the transfer by the destination amount and status, not by whether both chains update together. If the fill is pending, give the source transaction time to appear in the bridge tracker. If it is expired, follow the refund path shown for that deposit rather than sending a duplicate transfer.

Use this order:

• Choose the source and destination chains, token, and recipient.
• Review the quoted receive amount and fee, then submit the deposit.
• Check the source transaction and bridge status while the relayer fills.
• Confirm the destination balance; follow refund steps if the request expires.