How to Cross-Chain Swap on Relay - Instant Token Swaps Across 85+ Blockchains
A relay swap lets you exchange one token for another across different blockchains in a single transaction, without managing wrapped tokens, destination gas, or multiple bridge hops. Relay combines intent-based bridging with DEX meta-aggregation so a cross-chain swap completes in seconds across 85+ networks, often at a fraction of the cost of a traditional bridge. This guide explains how a relay swap works, how to perform one step by step, and how to keep your funds safe while swapping across chains in 2026.
For a broader overview of the network, see our main Relay cross-chain bridging guide. This page focuses specifically on the swap flow - the act of trading one asset for another across chains - rather than the protocol architecture covered there.
What Is a Relay Swap?
A relay swap is a cross-chain swap executed through the Relay App or Relay API. You specify the source token and chain, the destination token and chain, and the amount. Relay then returns a quoted rate from a solver who fronts the destination liquidity, and once you accept the quote and send the source assets, the solver delivers the destination tokens to your wallet.
Because the solver holds pre-positioned liquidity on the destination chain, the swap does not wait for cross-chain message passing or finality on the source chain. Small swaps often complete in seconds, and the DEX meta-aggregation layer sources the best price across major decentralized exchanges on both sides of the trade.
This is fundamentally different from a traditional cross-chain swap, where you would bridge an asset to the destination chain, then swap it on a DEX, paying two sets of fees and waiting through two confirmation windows. Relay collapses those steps into one intent.
Relay Swap vs Traditional Cross-Chain Swap
| Aspect | Relay Swap | Traditional Cross-Chain Swap |
|---|---|---|
| Steps | One transaction; one signature | Bridge, wait, swap, pay gas twice |
| Speed | Seconds for small swaps | Minutes to hours |
| Pricing | DEX meta-aggregation across 85 chains | Single DEX on destination chain |
| Destination gas | Sponsored by the solver | User must hold native gas on destination |
| Wrapped tokens | Not required | Often required for bridged assets |
| Fees | Often 80% lower than alternatives | Higher routing and on-chain costs |
How a Relay Swap Works Under the Hood
Understanding the mechanics helps you judge quotes and avoid mistakes. A relay swap moves through four stages.
1. Quote Request
When you enter a swap in the Relay App, the system requests quotes from solvers who maintain balances on the destination chain. Each solver returns a rate, an estimated delivery time, and a fee. Relay surfaces the best quote to you upfront, so you see the exact amount of destination tokens you will receive before you sign anything.
2. Intent Submission
Once you accept the quote, you sign a single transaction that sends your source tokens to a Depository contract. This is an intent - a signed instruction that says "deliver X destination tokens to my address if I deposit Y source tokens." You never hand custody to the solver directly; the Depository holds the deposit atomically.
3. Solver Execution
The solver sees your intent, validates it, and sends the destination tokens to your wallet from its own pre-positioned balance. Because the solver uses its own liquidity, delivery does not depend on the source chain reaching finality. The solver takes on the finality risk and is bonded, so it can be slashed if it misbehaves.
4. Settlement
After the source chain confirms, the solver claims your deposited source tokens from the Depository. Order validation and fee collection happen on a cheaper settlement layer, which keeps gas costs low on expensive chains. The net result is one user signature and near-instant delivery of destination tokens.
Step-by-Step: How to Do a Cross-Chain Swap on Relay
This walkthrough covers the consumer Relay App flow. Developers integrating swaps programmatically should use the Relay API instead, covered further below.
Step 1: Connect a Web3 Wallet
- Install Phantom or MetaMask, or use a wallet-compatible browser
- Make sure you hold the source token and enough native gas for the origin chain (for the single approval transaction)
- You do not need native gas on the destination chain - the solver sponsors it
Step 2: Choose Source and Destination
In the Relay App, select the source chain and token, then the destination chain and token. Relay supports 85+ networks including Ethereum, Solana, Arbitrum, Optimism, Base, Polygon, Avalanche, and BNB Chain. Enter the amount you want to swap.
Step 3: Review the Quote
Relay shows the quoted destination amount, the fee, the estimated delivery time, and the recipient address. Check all four carefully: the destination amount you will receive, the fee already deducted from the quote with no hidden costs, the delivery time (usually seconds for small swaps), and the recipient address on the destination chain.
Step 4: Sign and Send
Accept the quote and sign the single transaction. Your source tokens move to the Depository, the solver delivers destination tokens to your wallet, and the swap completes. For small swaps you will typically see the destination tokens arrive within seconds.
Step 5: Confirm Receipt
Switch your wallet to the destination chain and verify the tokens arrived. If a route is delayed, Relay provides a clear completion signal rather than leaving you guessing at confirmation progress.
Relay Swap Fees and Slippage
Relay swap fees are shown upfront and are already baked into the quoted destination amount, so the number you see is the number you get. Fees are often 80% lower than traditional bridge alternatives because order validation happens offchain and settlement is routed through a cheaper layer.
Slippage on a relay swap is determined by the DEX meta-aggregation layer, which sources the best price across multiple DEXs on both sides of the trade. For large swaps relative to pool depth, slippage can increase - always review the quoted destination amount and the minimum received before signing.
Supported Swap Routes
Relay supports cross-chain swaps across 85+ blockchains. Common routes include Ethereum to Solana (and back), Ethereum to Arbitrum, Optimism, Base, Polygon, Avalanche, and BNB Chain, Solana to EVM chains, L2 to L2 swaps such as Arbitrum to Base or Optimism to Polygon, and native token and stablecoin swaps across chains. Not every asset pair behaves identically - always verify your specific route is supported and review the quote before signing.
Relay API: Swap Integration for Developers
Developers can embed a cross-chain swap into any app with a single Relay API integration. The API handles routing, solver quoting, execution, and settlement, while exposing controls for slippage tolerance, execution speed, and recipient address. One integration works across 75+ chains, so teams can offer cross-chain swaps without building bridging infrastructure themselves. Typical use cases include in-app swap widgets, gasless onboarding flows where relayers subsidize destination gas, and cross-chain account abstraction where an account on one chain sponsors a swap on another.
Safety Checklist for Relay Swaps
- Use the official Relay App: Bookmark the correct URL and avoid phishing interfaces that mimic the swap UI
- Verify the recipient address: A cross-chain swap sends to the address you specify - check it on the destination chain
- Review the minimum received: For larger swaps, confirm the slippage and minimum destination amount before signing
- Start small: Test a new route with a small amount before swapping large value
- Check route support: Confirm both the source and destination token are supported on the route you want
- Understand solver risk: Swaps rely on bonded solvers today; decentralization is expanding via the Relay Protocol
Key Takeaways
- A relay swap is a single-transaction cross-chain swap powered by intent-based bridging and DEX meta-aggregation
- Solvers front destination liquidity, so small swaps often complete in seconds across 85+ blockchains
- Fees are quoted upfront and baked into the destination amount - destination gas is sponsored by the solver
- Review the quote, recipient address, and minimum received before signing every swap
- Developers can add cross-chain swaps to any app with a single Relay API integration
A relay swap makes a cross-chain swap as simple as a regular DEX trade - one signature, one quote, near-instant delivery. Start with a small test swap on your route, verify the recipient and minimum received, and scale up only once you are comfortable with how the flow works. For the full network overview, return to the Relay bridging guide, or see our Relay intents bridge guide for a deeper look at the intent architecture behind every swap.
Frequently asked questions
What is a relay swap?
A relay swap is a cross-chain swap where you specify a source and destination token and chain, accept a quoted rate from a solver, and sign one transaction. The solver delivers destination tokens from its own liquidity, so the swap often completes in seconds across 85+ blockchains.
How long does a relay swap take?
Small relay swaps usually complete in seconds because the solver holds pre-positioned liquidity on the destination chain. Very large swaps may take longer as solvers rebalance.
How much does a relay swap cost?
Fees are quoted upfront and are already deducted from the destination amount shown. Relay swap fees are often 80% lower than traditional bridge alternatives, and destination gas is sponsored by the solver so you do not need native gas on the destination chain.
Do I need gas on the destination chain to swap?
No. The solver sponsors destination gas, so you only need native gas on the source chain for the single approval transaction.