Gasless Trading: How to Swap Tokens Without Paying Gas
Sign a message instead of sending a transaction. A market maker executes your swap on-chain and covers the gas fee. You pay nothing except the swap price.
Key Takeaways
- Gasless swaps use EIP-712 signatures instead of on-chain transactions, so you pay zero gas
- Permit2 enables token approvals via signatures, eliminating the separate approval transaction
- A market maker (filler) executes your trade on-chain and absorbs the gas cost
- Gasless orders also provide MEV protection since they never enter the public mempool
Table of Contents
- What is Gasless Trading?
- How EIP-712 Signatures Work
- The Role of Permit2
- Step-by-Step on ChainBridge
- Supported Tokens and Chains
- Gasless vs Normal Swaps
- Limitations
What is Gasless Trading?
Every on-chain transaction on Ethereum requires gas -- a fee paid in ETH to compensate validators for processing your transaction. For a typical swap on Ethereum mainnet, gas can cost anywhere from $5 to $50+ depending on network congestion.
Gasless trading eliminates this cost entirely. Instead of submitting a transaction to the blockchain yourself, you sign a structured message that says: "I want to swap X tokens for at least Y tokens, and this offer expires at time Z." This signature is submitted off-chain to a network of professional market makers (fillers).
A filler picks up your signed order, executes the swap on-chain using their own ETH to pay gas, and delivers the output tokens to your wallet. The filler profits from the spread between their execution price and the price they give you. You receive your tokens without ever sending an on-chain transaction.
How EIP-712 Signatures Work
EIP-712 is an Ethereum standard for signing structured data. Unlike a raw message signature (which shows you an unreadable hex string), EIP-712 presents human-readable information in your wallet popup. You can see exactly what you are authorizing: the token amounts, recipient addresses, and expiration time.
When you sign a gasless swap order, the EIP-712 typed data includes:
The critical security property: your signature can only be used to execute this exact trade. A filler cannot modify the amounts or tokens. If market conditions change and the trade cannot be filled at your minimum price, the order simply expires.
The Role of Permit2
Traditionally, swapping an ERC-20 token requires two transactions: first an "approve" transaction to grant the DEX permission to spend your tokens, then the actual swap transaction. Each approval costs gas and is a potential security risk if you grant unlimited approval.
Permit2, developed by Uniswap, replaces this pattern. You approve Permit2 once per token (a single on-chain transaction), and then all future approvals for any protocol that supports Permit2 are done via signatures -- no additional on-chain transactions needed.
This means the first time you use gasless swaps with a new token, you pay one approval transaction. After that, every swap with that token is truly gasless -- just a signature.
Step-by-Step on ChainBridge
Here is exactly how a gasless swap works on ChainBridge:
Select Your Swap
Choose your sell token, buy token, and amount on the ChainBridge swap page. The interface will indicate if the pair is eligible for gasless execution.
Approve Token Access (One-Time)
If this is your first time swapping this token, you need to sign a Permit2 approval. This is a one-time signature (not a transaction) that allows the 0x protocol to access your tokens for swaps.
Sign the Order
Instead of submitting a blockchain transaction, your wallet will ask you to sign a structured message (EIP-712). This signature contains all the trade details: tokens, amounts, slippage, and expiration time.
Order Submitted Off-Chain
ChainBridge submits your signed order to the 0x gasless API. A market maker (called a "filler") picks up your order and executes it on-chain, paying the gas fee themselves.
Track Status in Real Time
ChainBridge provides real-time SSE status updates while your order is being processed. You will see when it is submitted, picked up by a filler, and confirmed on-chain.
Supported Tokens and Chains
Gasless trading is available on all chains supported by 0x Gasless API. Availability depends on filler activity and token liquidity.
Ethereum
USDC, USDT, DAI, WETH, WBTC, and most major ERC-20 tokens
Best gasless support due to high filler activity
Arbitrum
USDC, USDT, ARB, WETH, and popular L2 tokens
Fast execution (< 5 seconds typical)
Base
USDC, WETH, cbETH, and Base-native tokens
Growing filler network
Optimism
USDC, USDT, OP, WETH
Supported with moderate filler activity
Gasless vs Normal Swaps
Both approaches have trade-offs. Use this comparison to decide which is right for your situation.
| Feature | Gasless | Normal Swap |
|---|---|---|
| Gas cost to user | Zero | User pays (varies by chain) |
| Transaction type | Off-chain signature | On-chain transaction |
| Execution speed | 10-60 seconds typical | Depends on gas price and congestion |
| MEV protection | Yes -- off-chain order, no mempool exposure | Vulnerable unless using private mempools |
| Token support | ERC-20 tokens with Permit2 support | Any token including ETH |
| Native ETH swaps | Not supported (must use WETH) | Fully supported |
| Price | May be slightly worse (filler takes a spread) | Market price from aggregator |
| Failure mode | Order expires if no filler picks it up | Transaction reverts (gas still consumed) |
Limitations
Gasless trading is powerful but not universally applicable. Be aware of these constraints:
- No native ETH: You cannot sell native ETH gaslessly because ETH does not support EIP-712 permits. You must wrap it to WETH first (which costs gas).
- Filler availability: If no filler picks up your order, it expires after the timeout period. This is rare for popular pairs but can happen for exotic tokens or during extreme congestion.
- Slightly wider spread: Fillers need to profit from the spread to cover gas costs. For large trades, this spread is negligible. For very small trades, a normal swap might actually be cheaper on L2 chains where gas is already low.
- Token support: The sell token must support Permit2 or EIP-2612 permits. Most modern ERC-20 tokens do, but some older tokens (like the original USDT on Ethereum) may not.
- Execution time: Gasless orders are not instant. They typically take 10-60 seconds depending on filler competition and network conditions.
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Try Gasless Swaps on ChainBridge
Sign a message, skip the gas fee, and get your tokens. It is that simple.