Optimism is a popular Ethereum Layer 2 (L2) blockchain designed to increase scalability. As a result, bridging is an essential part of using the technology. Optimism increases efficiency by processing transactions off Ethereum and periodically syncing them. This results in transaction fees and processing speed being significantly lower than Ethereum, making Optimism one of the most popular Ethereum L2 solutions.
Blockchains are typically isolated systems and can't interact with other chains. The purpose of blockchain bridges is to address this issue. Through blockchain bridging, individuals can efficiently transfer their funds between different chains. These cryptocurrency bridges promote compatibility between blockchains and streamline the process of transferring digital assets. The future of decentralized applications (DApps) is multi-chain, as some chains are built for specific purposes.
Preparing for bridging: wallet and asset selection
Choosing the right wallet
The first step before using an Ethereum to Optimism bridge is to choose the right wallet.
OKX provides a highly secure and multi-chain OKX Web3 Wallet with all OKX accounts. It can safely store BTC or any other cryptocurrency for as long as needed. In addition, the OKX Web3 Wallet features bank-grade security and inbuilt access to hundreds of DApps and the OKX NFT Marketplace.
Selecting assets for bridging
Before bridging a cryptocurrency from one chain to another, the first task is to confirm that the asset is compatible. In this article, we'll be moving ETH from the Ethereum mainnet to Optimism. This process only requires ETH, as it’s the primary currency on both chains. On both the Ethereum blockchain and Optimism, ETH is used for covering gas fees.
To bridge a different asset like USDT, you must make sure that Optimism supports USDT. One easy way to do this is to check the bridge. If USDT is available, you should be able to bridge it. However, make sure you have ETH on Optimism to pay for gas fees after you bridge the USDT.
Exploring bridge services
Decentralized bridge services
Our top pick for a secure cross-chain bridge to transfer ETH to Optimism is OKX Swap. By collecting prices from multiple decentralized exchanges, OKX provides the most optimal path, reducing the impact of slippage and network charges.
Optimism also provides its own solution, Optimism Bridge. However, this option supports a limited number of cryptocurrencies and doesn't offer swapping services. Other options you can check out are Meson and Stargate.
Centralized bridge services
One simple method of connecting to Optimism is through the use of centralized exchanges. By depositing your ETH on OKX using one chain, you can then withdraw it using a different one. The following is a basic tutorial on how to bridge ETH from Ethereum to Optimism through OKX Exchange.
Step 1: Create an account on OKX.
Step 2: Once logged in, head to “Assets” on the top-right and select “Deposit.” If you don’t have ETH, buy some on OKX and skip the deposit step.
Step 3: Select “ETH” as the crypto and “ETH-ERC20” as the deposit network.
Step 4: Send ETH to the displayed address. It may take several minutes for the ETH to be credited to your account and become available for use.
Step 5: Once your funds are ready to be used, go back to “Assets” and select “Withdraw.”
Step 6: Select “ETH” as Crypto and the withdrawal method as “On-chain.”
Step 7: Enter your Optimism address and choose "ETH-Optimism" as the network. Enter the amount of ETH you wish to transfer to Optimism and select next. You'll then be prompted to verify your account, and the ETH should appear in your wallet in a few minutes.
Using an exchange to connect your assets is among the simplest approaches, as you don't encounter slippage or network fees.
Choosing a bridge service
Centralized and decentralized cryptocurrency bridges offer different benefits. Deciding between the two depends on your preferences. Decentralized bridges allow for faster movement between chains but may have high fees and slippage. When choosing a decentralized bridge, prioritize security and choose a reputable one with a strong track record.
Bridging process: a step-by-step guide
To bridge ETH to Optimism, you'll need to link your wallet and send the assets. We'll execute the bridging process by using OKX Web3 wallet and OKX Swap. The steps should be similar for other wallets or bridge services.
Connecting to a bridge service
Step 1: Head over to OKX Swap
Step 2: Select “Connect wallet” in the top right corner, and select “OKX wallet extension.” If you use another wallet provider like Metamask or Phantom, select “Other” and choose your wallet.
Step 3: Enter your OKX wallet password and click "Confirm" to connect your OKX wallet and OKX Swap.
Transferring assets to Optimism
After successfully connecting to OKX Swap, you can proceed to transfer ETH to Optimism.
Step 1: Adjust the bridge settings and specify the desired quantity of ETH to transfer in the "Swap & Bridge" section.
Select “Ethereum” as the “from” chain and type in the amount of ETH you want to bridge.
Select “Optimism” on the “To” chain and token “OP_ETH.” OKX Swap will automatically show you the amount of ETH you’ll get.
Step 2 (optional): This is an optional step. We advise you only do this if you understand slippage and bridges very well.
Network fee: the network fee for enabling blockchain bridging.
Slippage: slippage refers to the level of flexibility you're comfortable with in relation to fluctuations in prices. By choosing a slippage of 0%, OKX swap guarantees that you'll receive exactly 0.4982 ETH, as displayed. However, if you opt for a higher slippage, the transaction will be voided, and you'll incur the network fee. Allowing for some slippage is important when dealing with pools with lower liquidity levels.
Trading route: The OKX Swap isn't a bridge, but rather a DeFi aggregator that automatically selects the most suitable bridge to Optimism for you. However, you also have the option to manually change the service if you want to.
Step 3: Select “Swap across chains.” When your wallet shows, confirm the transaction.
OKX Swap is a convenient DeFi solution for transferring and exchanging your digital assets through multiple bridges.
In addition to OKX Swap, other bridges can function as bridges from Optimism to ETH. You must choose Optimism as the primary network and ETH as the secondary network.
Understanding fees and timelines
Fee structures explained
There are multiple fees involved in a decentralized bridging process:
Ethereum gas fees: The cost of transferring your ETH from your wallet to the bridge on Ethereum.
Bridge fees: OKX Swap serves as a bridge and swap aggregator, with the bridge charging a small fee for facilitating the bridging process.
Optimism transaction fees: Just like the gas fee in Ethereum, an Optimism transaction fee is required for transferring ETH from the bridge to your wallet.
Conversion fees: If you opt to switch cryptocurrencies during the process of bridging, there'll be an extra charge. For example, you can convert USDT on Ethereum to ETH on Optimism, but it will come with an additional fee for the conversion.
Before starting the transfer, you can view the detailed breakdown of conversion and bridge fees on OKX Swap. Keep in mind the Ethereum gas fee will only be displayed on the OKX Web3 Wallet pop-up when you confirm the transaction.
Expected transaction times
Just like the fee involved, transaction time also depends on multiple factors:
Ethereum confirmation time: The duration of transferring ETH from your wallet to the Bridge is dependent on the amount of gas used. With sufficient gas, this process should only take a few seconds.
Bridge processing time: The duration of transferring assets from one chain to another varies depending on the bridge used. For OKX Swap, this information can be found by selecting the trading route in the advanced options.
Optimism blockchain confirmation time: The ETH will be transferred to your Optimism wallet after the bridging process. As Optimism is known for its speed, you can expect the funds to arrive in just a few seconds.
Security measures and best practices
Providing secure transactions
When using a Cryptocurrency bridge, keep in mind that you’re engaging with a smart contract that has access to your wallet. Malicious smart contracts can be used to deplete wallet funds. To make sure your cryptocurrency transactions on bridges are safe, follow these guidelines:
Make sure you’re using a reputable bridge to Optimism like OKX Swap, which is well established in the market.
Don't use your primary wallet for interacting with bridges and other decentralized applications. Instead, keep a separate cold wallet for storing your assets.
Use tools like Revoke to remove access to your wallet once you’re done bridging.
Using a centralized exchange for bridging purposes is an effective method for reducing these risks. As a leading global cryptocurrency exchange, OKX employs world-class security measures to make sure worldwide users can buy and sell BTC safely and seamlessly. Visit our security of funds and Proof of Reserves page for more details.
Avoiding common pitfalls
Read on for some of the common pitfalls to avoid while you’re bridging your assets to Optimism:
Make sure to review all the fields you fill out. Once you confirm the transaction, there's no way to undo it.
Be mindful of the gas fees. During periods of high demand and congestion on the Ethereum network, gas fees may reach a high level. It's advised to either wait for the fees to decrease or use a centralized exchange for transactions.
High slippage and liquidity issues are another aspect to look out for. You may encounter significant slippage if you use an unfamiliar bridge or bridge to a coin with limited trading volume. To prevent this, restrict your bridging to assets with ample liquidity.
Troubleshooting and support
Common bridging issues and solutions
Stuck transactions are common and can occur when the gas fee for Ethereum isn't set correctly. If the gas is too low, the transaction will fail and the funds will be returned to your wallet. Transactions may also get stuck on congested cryptocurrency bridges. But, they're designed to handle these situations and will eventually be resolved with time.
Cross-chain compatibility: Make sure there's sufficient liquidity for the asset you’re bridging and that it’s compatible with the chain every time you bridge.
Where to seek help
The cryptocurrency community is known for being supportive. If you encounter any problems, you can easily seek assistance.
If you are using OKX Swap or OKX Exchange, you can visit OKX Support to see if your question has already been answered in the FAQ section. If you require further assistance, you can start a chat with the support team to address your concerns. Reliable cryptocurrency bridging services typically offer a support system. Make sure to only engage with official support materials and be cautious of fraudulent links.
© 2023 OKX. This article may be reproduced or distributed in its entirety, or excerpts of 100 words or less of this article may be used, provided such use is non-commercial. Any reproduction or distribution of the entire article must also prominently state:"This article is © 2023 OKX and is used with permission." Permitted excerpts must cite to the name of the article and include attribution, for example "Article Name, [author name if applicable], © 2023 OKX." No derivative works or other uses of this article are permitted.
