A cross-chain bridge is infrastructure that connects different blockchain networks, allowing users to transfer assets from one chain to another. With the development of multi-chain ecosystems, cross-chain bridges have become indispensable tools in DeFi. If you need to transfer assets between different chains, you can first visit the Binance Official Website and use the exchange's multi-chain withdrawal feature for simple cross-chain operations.
Why Do We Need Cross-Chain Bridges?
Different blockchain networks (such as Ethereum, BNB Chain, Solana, Arbitrum, etc.) are independent of each other. ETH on Ethereum cannot be used directly on BNB Chain, just as Chinese yuan cannot be spent directly in the United States. Cross-chain bridges act as "currency exchange counters" between these blockchains.
Common cross-chain needs include:
- Transferring USDT from Ethereum to BNB Chain to use PancakeSwap
- Moving assets from BNB Chain to Arbitrum to participate in DeFi
- Withdrawing from Layer 2 networks to the Ethereum mainnet
How Cross-Chain Bridges Work
Cross-chain bridges mainly implement asset transfers through the following methods:
Lock-and-Mint Model
The most common cross-chain method. Original tokens are locked on the source chain, and an equal amount of wrapped tokens are minted on the target chain. For example, after locking ETH on Ethereum, WETH is minted on BNB Chain. When redeeming, the wrapped tokens are burned and the original tokens are unlocked.
Liquidity Pool Model
There is a liquidity pool on both the source and target chains. Users deposit tokens on the source chain and withdraw from the pool on the target chain. This method is faster but requires sufficient liquidity support.
Atomic Swaps
Direct exchanges between chains through Hash Time-Lock Contracts (HTLC), without needing intermediaries. Highest security but complex to implement with limited applicability.
What Are the Major Cross-Chain Bridges?
- Official Bridges: Each chain's official cross-chain bridge, such as Arbitrum Bridge and Optimism Bridge — highest security but slower speed
- Stargate: A cross-chain bridge based on LayerZero, supporting multi-chain native asset transfers
- Across: A fast, low-fee cross-chain bridge focused on asset transfers between Layer 2s
- Orbiter Finance: Suitable for low-cost cross-chain transfers between Ethereum and Layer 2s
- Multichain (Closed): Once one of the largest cross-chain bridges, shut down in 2023 due to a security incident
Steps to Use a Cross-Chain Bridge
Using Stargate to bridge USDT from Ethereum to Arbitrum as an example:
- Visit the Stargate official website and connect your wallet
- Select the source chain (Ethereum) and target chain (Arbitrum)
- Choose the token (USDT) and enter the amount
- Confirm the cross-chain fees and estimated arrival time
- Click Transfer and confirm the transaction in your wallet
- Wait for the cross-chain transfer to complete, usually a few minutes to over ten minutes
Cross-Chain Bridge Fees
Using a cross-chain bridge incurs the following costs:
- Source Chain Gas Fee: The gas fee required to initiate the transaction on the source chain
- Cross-Chain Protocol Fee: The service fee charged by the bridge itself, typically 0.01%-0.1% of the bridged amount
- Target Chain Gas Fee: Some bridges automatically cover this; others require the user to have a small amount of gas tokens on the target chain
Total costs depend on the blockchain networks involved and the amount being bridged. Costs are highest when Ethereum mainnet is the source chain.
Cross-Chain Bridge Risks
Cross-chain bridges have long been one of the most vulnerable components in DeFi, with multiple major security incidents in history:
- Ronin Bridge: $625 million lost in 2022
- Wormhole: $320 million lost in 2022
- Nomad: $190 million lost in 2022
- Multichain: $126 million lost in 2023
These incidents demonstrate that cross-chain bridges are prime targets for hackers, and extra caution is needed when using them.
Safety Reminders
Be sure to note the following when using cross-chain bridges:
- Prioritize official bridges: Each chain's official cross-chain bridge offers the highest security — it's worth the trade-off even if slower
- Bridge in batches: Large amounts should be bridged in multiple transactions to reduce single-transaction risk
- Verify the target address: Confirm the receiving address on the target chain is correct — cross-chain transactions are irreversible
- Use exchange cross-chain: For mainstream tokens, using a centralized exchange's multi-chain deposit/withdrawal may be safer and more convenient
- Monitor project updates: Stay informed about the bridge's security audits and updates
- Check contract approvals: After bridging, check for unnecessary contract approvals. You can use the Binance Official App, Apple users refer to the iOS Installation Guide, and use the exchange's cross-chain withdrawal feature as an alternative
What's the Difference Between a Cross-Chain Bridge and Exchange Withdrawal?
Exchange withdrawal completes transfers between different chains through a centralized platform — simple but requires trusting the exchange. Cross-chain bridges are decentralized solutions that don't require trusting a third party but are more complex to operate. For mainstream tokens, exchange withdrawal is usually more convenient.
How Long Does a Cross-Chain Bridge Transfer Take?
It depends on the bridge used and the networks involved. Official bridges may take 7 days (e.g., Optimism withdrawals), while third-party bridges typically take minutes to half an hour. Faster bridges generally have weaker security assumptions.
Will Funds Be Lost If a Cross-Chain Bridge Transfer Fails?
Normally, no. If a cross-chain transaction fails, tokens on the source chain are usually automatically refunded. However, if the bridge itself has a security issue (e.g., a hacker attack), funds may be lost.
Can All Tokens Be Bridged Cross-Chain?
No. Cross-chain bridges typically only support specific token lists. Mainstream tokens (ETH, USDT, USDC, etc.) are available on most bridges, but niche tokens may need to be swapped for mainstream tokens on the source chain first.
Are Cross-Chain Bridges Safe?
Cross-chain bridge security varies by project. Official bridges are generally safest but have limited functionality. Third-party bridges are more convenient but carry higher risk. It's recommended to choose bridges that have undergone multiple audits, have been running for a long time, and have high TVL.