The Complete Guide to Crypto Bridges: Moving Assets Across Chains Made Simple

Want to stake ETH on Polygon, but all your funds are on Optimism? Or maybe you've found the perfect NFT on Base, but your ETH is stuck on Arbitrum? You try to move the funds around, and suddenly, you're neck-deep in confirmations, approvals, and waiting times. Why? Because blockchains don't naturally talk to each other.

Now, contrast that flow with a regular bank transfer: if you want to move $100 from Bank of America to Citibank, all you need to do is to open the bank app, tap transfer, and done. Your money appears instantly on the other side. No hoops, no stress.

This stark difference exists because moving crypto across chains - even when it's the same ETH within the Ethereum ecosystem - requires bridging the communication gap between separate networks.

This is where crypto bridges come in. These protocols break down network barriers to make moving coins across chains as seamless as that bank transfer. 

If you’re new to the concept of crypto bridging, don’t worry; we've got you. This guide will break down what a crypto bridge is, how it works, and why you need it. 

Let’s dive in.

What exactly is a crypto bridge? Think of it like a digital highway system connecting different blockchain cities. Just as highways let people and goods move between cities, crypto bridges create pathways for moving crypto between otherwise isolated blockchain networks.

In the rapidly expanding web3 landscape, we now have:

Each of these chains is like its own city with unique rules and systems. Without bridges, your assets would be stuck in whichever 'city' they started in. Bridges solve this problem by creating secure routes between chains, enabling your crypto to move freely throughout the entire web3 ecosystem.

Let's look at a practical example: Say you have ETH on Optimism that you want to use for staking on Polygon. Without a bridge, you'd need to:

A bridge creates a direct path, letting you move your ETH straight from Optimism to Polygon in a single transaction. It's like having a teleporter between blockchain cities instead of taking the long way around.

However, here's the catch: while bridges make asset transfers possible, traditional bridges often introduce their own headaches. They can be slow (taking hours or even days), complicated (requiring multiple confirmations), and some won’t win any awards for security.

So yes, bridges are better than no bridges - but there's an even better way to bridge crypto. 

This is where Across comes in. By leveraging game-changing crosschain Intents, powered by the ERC-7683 standard, Across fundamentally reimagines how crypto bridging should work. Instead of navigating complex bridging processes, users simply state what they want - like "move my ETH from Optimism to Polygon" - and the network handles everything else automatically.

Think of it as the difference between giving turn-by-turn directions and telling your rideshare app where you want to go. With traditional bridges, you manage every step. With Across’ Intents-based system, you specify the destination and let the system handle the journey.

The explosive growth of Layer 2s and new chains has created a multichain reality where opportunities are scattered across different networks. 

Think of it like this: the best staking yields might be on Polygon, the hottest NFT drops on Base, and the most profitable DeFi strategies on Optimism. Bridges are the first step into crosschain interoperability, and without them, you'd be locked out of most of these opportunities.

Here's exactly why crypto bridges matter and how they make your web3 life easier

Asset mobility forms the foundation of why bridges matter in today's crypto market. In a multichain world, keeping your assets confined to a single chain is like having money locked in a bank that only operates in one city. Bridges unlock the ability to use your assets wherever and however you want. Whether you're looking to participate in governance voting, stake your tokens, or try out a new DeFi protocol, bridges ensure your assets can flow freely to where they're needed most.

Cost optimization represents another crucial advantage of bridging capabilities. Gas fees can vary dramatically between chains, with Layer 2 solutions often offering significantly lower transaction costs than Ethereum mainnet. By bridging assets to more cost-efficient chains, users can dramatically reduce their operational costs. This is particularly important for frequent traders and DeFi users who might execute multiple transactions daily.

This is an important one on two fronts:

Price differences for the same token often exist across protocols on different chains. Think you spotted one? Bridges lets you move fast to capitalize on arbitrage, level up your portfolio, and help balance the market.

Risk management becomes more sophisticated with bridging capabilities too. Instead of having all assets exposed to the risks of a single chain, users can diversify across multiple networks. This provides protection against chain-specific issues like network congestion or technical problems. If issues arise on one chain, assets can be quickly moved to more stable networks. Additionally, accessing multiple DEXs and lending platforms across different chains provides better liquidity options and more stable trading conditions.

Got voting rights on one chain but want to participate somewhere else? With crypto bridges, users can retain voting power while interacting with ecosystems outside their asset’s native chain. Bridges ensure your say (and assets) matter wherever you go.

Crypto bridges help scale the web3 ecosystem by letting assets flow to less congested chains. By spreading activity across multiple networks, bridges reduce bottlenecks and make transactions faster—effectively growing the entire ecosystem. As the pie gets bigger, everyone gets a larger slice.

Bridging your assets doesn’t just unlock new ecosystems; it might also qualify you for rewards like airdrops. Many projects reward users for interacting with specific chains or dApps. By bridging assets to new ecosystems, you can qualify for these incentives and take advantage of rewards across multiple networks. 

Thanks to intuitive interfaces, bridging crypto has become relatively simple for users on the surface. But what happens under the hood is more complex - and understanding this can help you make better decisions about which bridge to use.

Older crypto bridges use a basic 'lock and mint' system. When you want to move ETH from Optimism to Polygon, traditional bridges lock your ETH on Optimism and mint an equivalent "wrapped" version on Polygon. Think of it like checking your coat at a fancy restaurant - you give them your coat and get a claim ticket. The problem? Your coat (or, in this case, your crypto) is sitting in a centralized location, creating a tempting target for thieves.

Some bridges try to improve on this by using more sophisticated message-passing systems between chains. While this can work, it often leads to long waiting periods and complex verification processes. It's like sending a package internationally - sure, it'll get there eventually, but you'll spend a lot of time tracking it and waiting for customs clearance.

This is where Intents-based bridging fundamentally changes the game. Instead of locking assets or relying on complex messaging systems, Across lets you express what you want to achieve - "move ETH to Polygon" - and handles everything automatically. The system uses a network of relayers who compete to fulfill your request quickly and cheaply, similar to how rideshare drivers might compete to give you the best service.

By abstracting away these details, Across’ Intents-based infrastructure delivers fast, safe, simple, and more cost-efficient crosschain transfers. The result? Your assets move between chains in seconds, not hours or days, and you don't have to worry about complicated processes or security risks from locked funds.

We’ve mentioned “message-based” a few times now. Let’s break down these more traditional methods for comparison.

Traditional bridges rely on message-based systems to transfer assets or data between chains. These include:

Message-based bridging has enabled countless crosschain transfers and helped considerably grow the crypto interoperability space, but it could be a better system. Message-based bridging methods often come with risks like delays, high costs, and vulnerabilities. 

Across’ Intents-based system resolves these prevalent pain points by removing complexity, mitigating security risks, and optimizing performance. Across isn’t just simplifying bridging—it’s redefining how blockchains connect and offering a solution that scales with the growing complexity of Web3.

Here’s how Intents-based bridging sets itself apart:

In the world of crypto bridges, you'll encounter two main types: custodial and non-custodial. Let's break down what these mean and why the difference matters for your assets.

Think of custodial bridges like traditional banks. Just as banks hold and manage your money, these bridges take custody of your crypto during transfers. A perfect example is Wrapped Bitcoin (wBTC). When you want to use Bitcoin on Ethereum, custodians like BitGo:

Benefits:

Limitations:

Non-custodial bridges, on the other hand, rely on smart contracts and protocols to manage the bridging process. This decentralized approach enhances transparency and security but can be more complex for newcomers. 

An example here would be the Polygon Portal. This bridge has no central authority that holds custody of the funds. It connects Polygon to Ethereum via smart contracts, enabling users to move assets between the networks. 

Benefits:

Limitations:

Across lands within this non-custodial framework and takes it further with Intents. As previously mentioned, with Intents, users simply define their desired outcome (state their Intent), and the system handles the rest securely and efficiently without a central authority.  By optimizing non-custodial benefits while eliminating the usual complexities, Across offers a faster, more user-friendly experience than other non-custodial bridges.

When choosing a bridge, consider what matters most to you - convenience, security, speed, or decentralization. While custodial bridges might seem simpler at first, non-custodial Intents-based solutions like Across offer the best of all worlds: simplicity without sacrificing security or speed.

Bridges are powerful tools for navigating the multichain world, but like any web3 service, they come with important considerations. Let's explore what you should think about before choosing a bridge and how new Intents-based solutions are addressing traditional bridging challenges.

Traditional bridges have become prime targets for hackers due to the large amounts of locked assets they hold. Just as a bank vault full of cash attracts attention, bridges holding millions in crypto attract sophisticated attacks. Even non-custodial bridges can face vulnerabilities in their smart contracts - we've seen this with several high-profile bridge hacks in recent years.

How Across Mitigates This

With traditional bridges, you often face an unfortunate choice: wait longer for lower fees or pay premium rates for faster transfers. Some bridges make you wait days for confirmations, while others charge hefty fees for quicker service. Network congestion can make these delays and costs even worse. In addition, many traditional bridges require users to navigate complex, multi-step processes that can overwhelm beginners. This complexity isn't just frustrating - it increases the risk of user error and can lead to failed transfers or lost funds.

How Across Simplifies This

It isn't uncommon for network congestion to lead to transaction delays, especially on popular chains. These delays often stem from inefficient systems that process transactions sequentially or rely on limited liquidity pools. Bridge performance also depends heavily on available liquidity. Traditional bridges often struggle during high-demand periods, leading to delayed transfers or excessive fees. Some bridges maintain separate liquidity pools for each chain, fragmenting capital and reducing efficiency.

How Across Speeds Things Up

The complexity of bridging crypto can make the process time-consuming, cumbersome, and confusing. It’s not unusual for bridging to result in high transaction costs and delayed or even incorrectly executed transfers for the user.

But using a crypto bridge doesn’t have to be daunting.

With the right approach and a few attempts, it can feel as straightforward as any other transaction.

Check out our step-by-step guide to get you started.

As web3 expands, crypto bridges are becoming essential tools for navigating a multichain crypto landscape. They allow users to leverage assets across different networks, participate in unique blockchain-specific ecosystems, and maximize financial opportunities in DeFi.

Hopefully, this guide has helped you feel more prepared to dive into the wide world of crypto bridging. But if you’re looking for the most simple bridging solution, an Intents-based framework, like that available from Across, might be the best option.

By leveraging crosschain Intents, Across offers an innovative approach that simplifies swapping across networks and redefines the crypto bridging experience.

While traditional bridges struggle with security risks, high costs, and frustrating delays, Across takes a fundamentally different approach. By leveraging Intents-based bridging, Across delivers what users actually need: fast, secure, and hassle-free movement between chains.

Here's what sets Across apart:

Traditional bridges can keep you waiting for hours or even days. Across? Just 2 seconds. That's not a typo - you can move assets between chains in the time it takes to read this sentence. Through our competitive relayer network, your transactions get processed almost instantly, letting you seize opportunities the moment they arise.

Instead of creating vulnerable honeypots of locked assets, Across uses a decentralized network of relayers who compete to fulfill your transfers. Your assets move directly between chains without getting stuck in bridge contracts. Better yet, relayers take on the finality risk instead of you - they front the capital while waiting for transaction verification.

Forget about unpredictable fees and hidden costs. Across transfers cost just $0.04 on average. Our relayer bidding system ensures you always get the best price, while our optimized settlement process keeps gas costs minimal.

Why navigate complex bridging processes when you can simply state what you want to achieve? Want to stake ETH on Polygon? Buy an NFT on Base? Just specify your goal and let Across handle the rest. No more juggling approvals or tracking transactions across multiple interfaces.

Across isn't just another bridge - it's a glimpse into the future of how blockchain networks should interact. By focusing on user intents rather than mechanical transfers, we're building the infrastructure that will make web3 accessible to everyone.

Ready to experience the difference? Whether you're a DeFi enthusiast chasing yields across chains, a trader looking for efficient arbitrage routes, or simply someone who wants their crypto to move as easily as their bank balance, Across has you covered.

Visit Across today and join the thousands of users who've discovered that bridging doesn't have to be complicated.

Still have questions about crypto bridges? Here are answers to the most common questions:

Is bridging crypto safe? 

Bridging crypto comes with varying levels of risk depending on the type of bridge you use. Traditional bridges that lock assets can be vulnerable to hacks. Across minimizes these risks through its Intents-based system, in which no assets are locked in bridge contracts. Instead, a network of relayers competes to fulfill transfers, with relayers taking on the finality risk rather than users.

How long does bridging crypto take? 

Bridge transfer times vary significantly. Traditional bridges can take hours or even days to complete transfers, especially when using Optimistic Rollup native bridges (up to 7 days). Across completes most transfers in about 2 seconds through its optimistic verification and competitive relayer network.

How much does it cost to bridge crypto? 

Bridge fees typically include gas costs and bridge-specific fees. While some bridges charge high fees for faster service, Across transfers cost just $0.04 on its median transfers. The exact cost depends on network conditions and the chains involved, but Across's relayer bidding system ensures you get the best available price.

Which chains can I bridge between? 

The chains you can bridge between depends on the bridge you're using. Across currently supports transfers between major EVM chains, including Ethereum, Arbitrum, Base, Optimism, Polygon, and several others. The network continues to expand to support more chains.

What's the difference between custodial and non-custodial bridges? 

Custodial bridges require you to trust a third party with your assets (like BitGo for WBTC), while non-custodial bridges use smart contracts to handle transfers without a central authority. Across is non-custodial but takes things further with Intents-based bridging, combining the security of non-custodial systems with the simplicity of custodial ones.

Can I bridge any type of token? 

Not all tokens can be bridged. Most bridges support major tokens like ETH, USDC, and WBTC. Across supports these popular tokens and continues to add support for more assets based on user demand and security considerations.

What happens if my bridge transfer fails? 

The outcome depends on the bridge you're using. With traditional bridges, failed transfers can be complex to resolve and might require manual intervention. With Across, the relayer network ensures transfers complete successfully, and in the rare case of issues, the relayer bears the risk rather than the user.

Is Intents-based bridging different from regular bridging? 

Yes, significantly. Traditional bridges require users to manage complex processes and often lock assets in contracts. Intents-based bridging lets users simply specify what they want to achieve (like "move ETH to Polygon"), and the system handles all the complexity automatically. This means faster transfers, better security, and a much simpler user experience.

Do I need to bridge my crypto? 

If you want to use your assets on different chains—for example, to access better yields, participate in new DeFi protocols, or buy NFTs on specific marketplaces—you’ll need to bridge. Bridging lets you take advantage of opportunities across the entire web3 ecosystem rather than being limited to a single chain.