What Is a Blockchain Bridge?
| KEY TAKEAWAYS: |
| — Different blockchain networks do not speak the same language, and as such, moving assets between them can be difficult. — Crypto today is diving head-first to make everything interoperable—a multi-chain, seamless ecosystem that benefits and gives users the best of all chains. — Blockchain bridges are the key to unlocking interoperability between individual networks. They vastly improve the web3 experience and increase utility for users for multiple functions across chains. |
We love a good blockchain: distributed, decentralized, digital technology, designed to give control back to the people. But while a lot is going for blockchains as we know it, there are still kinks that need ironing out. One of the biggest ones is that many of the blockchains we know and love are self-contained ecosystems that can’t operate with other networks. It’s a problem of interoperability.
Think of each blockchain—like Bitcoin or Ethereum—as its own little island. They’re independent places that give people all the benefits of crypto, but they don’t connect to each other. That’s a problem because web3 has tons of blockchains, and there is a huge need and utility in sharing value across each other.
Blockchain bridges are like simple bridges between these islands. They let you move your crypto from one place to another—like sending Ethereum to Polygon for cheaper fees or shifting an NFT to Solana to sell it. Without bridges, you’re stuck on one island, missing out on what’s happening elsewhere. With them, everything links up, making it easy to use the best parts of every blockchain.
The Need For Blockchain Interoperability
Going multi-chain means better opportunities for both developers and users, and most web3 projects nowadays try to deploy their dApps on various chains. Moreover, different blockchains serve different purposes and have specialized functions that are suited to that particular blockchain. Think Ethereum for its smart contracts or Cardano for its native staking capabilities and so on.
Put simply, being stuck to a single chain locks the project out of the benefits of other blockchains. Each blockchain has its own language, and they aren’t all cross-compatible.
Let’s look at Bitcoin, it is still the most popular blockchain network to date. Then let’s take another popular network, Ethereum. Although they are both important, you can’t just send Bitcoin to an Ethereum account. These two chains are not interoperable. Not just that, functions like a whole range of different types of smart contracts that make ETH so valuable aren’t applicable to Bitcoin.
Decentralization, away from banks and middlemen, is the defining mission of blockchain. But, if users need to lock themselves into a specific network to access the full ecosystem of platforms and services, we’ll once again be centralized. In this scenario, the only difference is that the deciding factor is a blockchain rather than a bank. This is directly the opposite to most crypto enthusiast’s aims, and as such, innovators tried to find the solution to this problem.
So how do we go about moving assets between different blockchain systems to promote a multi-chain future?
This is where blockchain bridges come in.
What Is a Blockchain Bridge?
A blockchain bridge solves the problem of inter-network communication by offering a way to connect isolated blockchains with each other. Like any physical bridge, a blockchain bridge acts as the missing link between two blockchain ecosystems, making the transfer of information, data and tokens across them fairly easy. It’s a huge deal in the world of DeFi because it introduces connections that instantly change how stores of value move in web3.
What is a Blockchain Bridge For?
You might be thinking, “But why is this actually important? Surely one could just swap their tokens for another currency on an exchange?”
Well, the answer comes down to a couple of factors: convenience, and cost. It’s not only inconvenient for users to swap tokens around on crypto exchanges, but it gets expensive too. Crypto gas fees and other platform-based charges can be high. Since transaction fees are required not just for making the swap, but also for moving tokens around between various wallets or platforms as you do so, the cost adds up. Using a blockchain bridge instead makes the process seamless. Plus, they allow you to convert your crypto into a blockchain compatible wrapped coin in just one transaction.
How Does a Blockchain Bridge Work?
How Does a Blockchain Bridge Work?
So you might be wondering how blockchain bridges actually manage to send assets across incompatible blockchains. And the simple answer is, they don’t.
Instead, blockchain bridges work via smart contracts, which are essentially a compilation of computer code. When you want to move assets from one chain to another, the blockchain bridge locks up your funds within its smart contract. In return, you receive the same amount in wrapped crypto on your target chain. This wrapped token represents the same value as the asset you locked up in the contract. Put simply, wrapped crypto represents the native coin of one network (such as Bitcoin) while living on another (like Ethereum).
So let’s see how this works in practice.
Say you wanted to send someone some Bitcoin on the Ethereum network. First you would need to find a Bitcoin-Ethereum blockchain bridge. Once you locked up your funds in the platform’s smart contract, you would receive wrapped bitcoin (WBTC) on the Ethereum network.
With your WBTC on the Ethereum network, you could use it as you would any other of Ethereum’s tokens. This is because WBTC is essentially an ERC-20 token and operates seamlessly with Ethereum’s ecosystem. Once in the ecosystem, you can also swap or sell those tokens like any other asset on the Ethereum network. You can even use it for projects or platforms.
If you want to get your BTC back, you send your WBTC back to the bridge (where it is burned to protect the supply and value). As a result, the BTC you locked in at the bridge is unlocked and comes back to you for use.
Types of Blockchain Bridges
Blockchain bridges generally fall on a spectrum from centralized to decentralized. The three primary types of bridges are trusted (centralized) bridges, trustless (decentralized) bridges, and cross-chain messaging protocols.
Each functions differently and has distinct advantages and disadvantages.
Trusted (Centralized) Bridges
Trusted bridges rely on central authorities or a closed group (federation) to manage the bridging process. Users deposit their assets with this custodian, who is trusted to mint and release the assets on the target chain. In other words, a third party holds your funds and operates as the bridge.
How it works: You send your tokens to an address controlled by the bridge operator (could be a single company or a federation of a few parties). The operator confirms the deposit and mints a wrapped version of your asset on the destination chain for you to use. When you bridge back, the wrapped tokens are burned and the original tokens are released by the custodian.
Types of trusted bridges: Some are run by a single custodian (fully centralized), while others use a multisig federation of validators:
- Custodial bridges: A single entity holds custody of assets and issues wrapped tokens. For example, Wrapped Bitcoin (WBTC) is issued by a custodian (BitGo) who holds the equivalent BTC in reserve.
- Federated bridges: A set of known validators collectively control the bridge. These are more decentralized than a single custodian but still require trusting the federation. Wormhole is an example that uses 19 ‘guardians’ (validators) to secure its transfers.
| Pros | Cons |
| Faster and simpler to implement since operators manage the verification off-chain. | Counterparty risk: the operator could mishandle, steal funds, or become hacked. |
| Straightforward transfers if the custodian is trustworthy; users don’t manage complex systems themselves. | Single point of failure: compromised custodian or validators can result in loss of all bridged assets (e.g., stolen private keys). |
| A central operator can quickly add support for new assets or chains through manual processes. | Against blockchain’s decentralization ethos: users must trust a third party, sacrificing self-custody and security over the long-term. |
Trustless (Decentralized) Bridges
Trustless bridges remove centralized custodians by using smart contracts, cryptography, and algorithms to secure transfers. They are called “trustless” (or non-custodial) because users do not have to trust a middleman; the system is secured by the blockchain networks and code itself.
So, instead of a person or group holding your funds, a smart contract on Chain A locks your asset and triggers a cryptographic proof. This proof is relayed to a contract on Chain B, which then mints a wrapped asset for you on Chain B, and voila, you have bridged your funds.
The transfer is managed by special participants called relayers (or oracles, or validators), who watch one blockchain for activity (like when you lock tokens), and then automatically send proof of that event to the other blockchain.
This proof is then checked automatically by code, without human involvement. When you want your original tokens back, the wrapped tokens on the second blockchain are burnt, and your original tokens are unlocked for use again.
But like all things, there is a catch to trustless systems too. While called “trustless,” in reality users must trust the correctness of the smart contract code and often the honesty of a set of relayers. If the bridge design itself is flawed, funds are at risk. For instance, some “trustless” designs still depend on a majority of certain nodes acting honestly (just like a federation) unless they implement truly trust-minimized light clients.
Moreover, lots of people may not have the technical know-how to dive deep into these smart contracts and understand exactly what happens to their funds once they approve the bridging transactions. So, as always in crypto – DYOR is king.
| Pros | Cons |
| No need to trust a single entity; security relies solely on blockchain and smart contract code. Funds remain under your control, aligning with self-custody. | Complex code and cryptography increase the chance of bugs, making bridges more vulnerable to exploits. |
| Open-source and transparent; anyone can verify how the bridge functions. No hidden third-party control. | Can be slow or expensive due to the complexity of verifying proofs on-chain, limiting the number of chains supported. |
| Decentralized design makes the bridge difficult to shut down, as it relies on multiple independent nodes rather than a single company or server. | Difficulty verifying blockchain states across networks may require partial reliance on external participants, reducing security or decentralization. |
Cross-Chain Messaging Protocols
Cross-chain messaging protocols take the concept of bridges beyond just token transfers, enabling general communication between blockchains.
Unlike regular bridges that only transfer tokens, cross-chain messaging protocols can move almost any kind of data or instructions between blockchains. Essentially, they allow one blockchain to trigger actions or smart contracts on another blockchain, as if they were part of the same system.
These protocols set up a framework where messages (which could be token deposit events, contract function calls, or any data) are securely passed from one chain to another. Implementations vary:
Light Clients and Relays:
Each blockchain checks events directly from the other blockchain using simplified verification methods called “light clients.” Examples include Cosmos’s IBC and Near’s Rainbow Bridge.
Validator or Relayer Networks:
A group of independent nodes watches events happening on one blockchain and collectively verifies them to pass messages securely to another blockchain. Examples are Axelar, LayerZero, and Wormhole.
Main Chain or Hub Model:
In this model, one central blockchain acts as a communication hub, securely routing messages between multiple connected blockchains. Polkadot’s relay chain and Ethereum’s planned CCIP (by Chainlink) follow this approach.
A key aspect is they strive for generalizability – not just transferring one specific asset, but any payload. With these protocols, you could initiate a trade on a DEX on chain A from chain B, or send an NFT from Solana to Ethereum, or trigger an action on another chain when certain conditions are met on the origin chain.
| Pros | Cons |
| Lets smart contracts communicate across different chains, enabling cross-chain applications and services. | Often still relies partially on external parties (relayers/oracles), introducing centralization or security risks. |
| Connects multiple blockchains together efficiently, removing the need for separate bridges between each chain. | Can be slower and costlier due to complex validation, leading to delays or higher fees. |
| Can transfer any type of data—not just tokens—including NFTs, votes, or other important information. | Complex to integrate: Each blockchain may need specialized adjustments, causing fragmentation. |
| When properly designed, security can closely match that of the underlying blockchains themselves. | Higher development risk: Advanced functionality increases potential for hidden bugs and vulnerabilities. |
Blockchain Bridge Use Cases
Blockchain bridges have evolved far beyond their initial role of wrapping cryptocurrencies, and are now the most efficient way to properly experience web3’s multichain interoperability. Bridges have transformed from a niche tool into an essential infrastructure for connecting previously isolated blockchain environments.
Wrapping—converting tokens like Bitcoin, Ethereum, and others for use on different blockchains—remains important though. It enables access to decentralized applications (dApps), better interest rates, and broader ecosystem participation.
However, the utility for bridges now expands to power cross-chain DeFi, allowing users to optimize yields, enhance liquidity, and craft complex strategies across multiple blockchain ecosystems.
Similarly, they also enable NFT transfers, letting your digital assets flow seamlessly between networks.
Beyond individual use cases, blockchain bridges are driving realistic progress and innovation across industries and technologies.
Take enterprise blockchain integration, for example. Cross-chain bridges link private and public networks to support hybrid applications, streamline supply chain solutions, and accelerate institutional adoption.
For more context, take China’s Blockchain-based Service Network (BSN) — it integrates various blockchain frameworks to provide a unified platform for developing and managing blockchain apps. It supports both private and public blockchains, allowing businesses and governments to deploy apps efficiently. BSN has been used to streamline supply chain management and improve cross-border trade by providing a standardized blockchain infrastructure.
In governance, bridges facilitate cross-chain DAOs and coordinated voting, aligning policies and decision-making across disparate chains. Additionally, they tackle scalability and performance challenges by distributing transaction loads, supporting L2 solutions, and reducing dependency on a single chain’s capacity.
Bridges are the backbone to the multi-chain future that is currently being built in web3. But make no mistake—there have been significant losses incurred in crypto to get to this point of open functionality. Let’s take a look at some of these.
Key Hacks in Blockchain Bridge History
Blockchain bridges are crucial but have historically been vulnerable. The total amount lost due to bridge hacks in Web3 up to 2025 is approximately $3 billion! Let’s methodically examine some significant bridge exploits and their root causes:
1. Ronin Bridge Hack (March 2022) — $624M Lost
The Ronin Network, powering Axie Infinity, lost $624 million (173,600 ETH and 25.5M USDC) due to compromised private keys. The bridge’s security depended on just nine validator nodes, requiring five signatures to authorize withdrawals.
The attackers, identified as the Lazarus Group (North Korea-linked), socially engineered operators, obtaining control of five validator keys (four from Sky Mavis, one from Axie DAO). This breach nullified the bridge’s multi-signature security mechanism, enabling unauthorized withdrawals.
Critically, Ronin’s security flaws had these factors in common:
- Centralization: Power concentrated within Sky Mavis validators.
- Inadequate key security: Insufficient operational protection of private keys.
- Monitoring gaps: The theft remained undetected for nearly a week.
Your private keys represent absolute authority. If keys are compromised, sophisticated infrastructure is irrelevant. Decentralization, rigorous key management, and detailed monitoring are essential for security. Post-hack, Ronin diversified validators and improved vigilance, highlighting that bridges remain vulnerable as long as private key management is weak.
2. Wormhole Bridge Exploit (February 2022) — $320M Lost
The Wormhole Bridge, linking Ethereum and Solana, suffered a $320 million loss (120,000 WeETH minted improperly) due to a critical smart contract flaw. Attackers exploited incorrect signature verification in Wormhole’s Solana-based contract, minting tokens without corresponding ETH deposits. By submitting forged validation signatures, the attacker bypassed checks, creating tokens out of thin air.
Immediate consequences:
- Circulation of unbacked tokens, risking contagion in Solana’s DeFi ecosystem.
- Swift intervention by Wormhole’s parent company prevented broader market fallout by replenishing lost ETH.
Lesson: Even “trustless” bridges are subject to catastrophic smart contract vulnerabilities. Meticulous code auditing, formal verification, clear signing, and rigorous testing should be standard in the industry, but it isn’t all the way implemented. Vulnerabilities within intricate validation logic can lead to systemic risks across multiple chains.
3. Nomad Bridge Hack (August 2022) — $190M Lost
The Nomad bridge hack illustrates the catastrophic outcomes of flawed smart contract upgrades. Nomad lost around $190 million due to a seemingly minor logic error introduced in a June 2022 upgrade. The error—stemming from improper message validation—allowed anyone to replicate valid transaction data, substituting their own address, effectively creating a public and chaotic looting scenario.
This unprecedented “copy-paste” attack saw over 1,100 transactions rapidly siphoning assets. Unlike complex exploits, Nomad’s vulnerability was trivial yet devastatingly effective, highlighting how simple oversights can obliterate bridge security.
Lesson: Rigorous, systematic testing of every smart contract upgrade is critical. Enhanced upgrade protocols, thorough audits, and circuit breakers for unusual withdrawals have become necessary protective measures.
Ledger + LiFi: Cross-Chain Made Easy & Secure
Given the risks that bridges face, using a trusted aggregator designed specifically for secure bridging becomes crucial. LiFi, integrated directly into Ledger Live, offers exactly this—a security-first approach to cross-chain transfers. LiFi selects and aggregates multiple trusted bridges, automatically choosing the safest, most efficient path for your assets.
Combined with Ledger’s industry-leading hardware wallets, transactions remain fully under your control and transparently verifiable through clear signing directly on your Ledger device screen. This integration ensures your private keys stay secure while making complex cross-chain swaps easy, safe, and stress-free.
Why Ledger Is Your Safest Bet For Bridging
Ledger Live’s partnership with LiFi represents the safest way to bridge your crypto, ensuring security without sacrificing convenience or flexibility, essential for a thriving multichain future. But the ease-of-use and utility does not stop at just the ecosystem. Ledger’s next- generation devices, Ledger Stax and Ledger Flex represent an even more trusted solution to signing transactions. You can now verify each transaction on the industry-first e-ink secure touchscreens on both devices—meaning you don’t have to rely on the vulnerable screens of your everyday gadgets like laptops or cell phones.
This integration ensures private keys never leave the Ledger device, completely eliminating risks like phishing seen in major exploits such as the Ronin hack. Ledger Live supports clear signing, meaning transactions appear in human-readable form directly on the hardware wallet’s secure touchscreen, drastically reducing the risk of signing malicious transactions or being deceived by compromised computers.
Ledger devices independently parse and verify each step of complex multi-chain swaps, validating destination addresses and transaction parameters to ensure accuracy. All smart contracts involved are pre-verified and whitelisted within Ledger’s ecosystem, reinforcing transaction trustworthiness. By pairing LiFi’s bridge aggregation capabilities with Ledger’s meticulous security measures and user-friendly touchscreens, Ledger Live delivers the safest, simplest, and most transparent way for users to confidently move assets across multiple blockchain networks.
So, private keys secured offline plus transactions signed clearly and a secure touchscreen to go with it—you cannot lose sleep over your funds in this trifecta!
Bridging is made easier than ever—so why wait? Grab a Ledger device today and relax knowing your funds are always secure when using Ledger + LiFi.
How To Bridge Your Assets On Ledger Live
Before you can see the LiFi integration on Ledger Live, you may need to check if your Ledger Live version is up to date and if your Ledger device is running the latest OS (firmware) version. Once checked and updated, you can follow the steps below to easily swap across chains.
Step 1: Launch LI.FI in Ledger Live
- Open Ledger Live.
- Go to the Exchange section inside Ledger Live:
- Ledger Live for PC: Open the Exchange tab on the left panel.
- Ledger Live for smartphone: Tap the arrow icon at the bottom of the screen and select the “Exchange” button .
Step 2: Select crypto assets to exchange
- In the “You are sending” field , specify the crypto asset for exchange and the account with it, then enter the transaction amount.
- In the “You receive” field , specify the crypto asset and the account to receive.
Important: if there is no account for the required coin, click “Add account” .
Step 3: Select LI.FI as your carrier
- The app will display current rates from different operators next to the exchange details. Select LI.FI to complete the transaction.
- Click “Exchange via LI.FI” .
Step 4: Approve access to your tokens
- If you choose to exchange a token that is not a native cryptocurrency of the network, you will need to grant access to LI.FI via token approval. This will give the platform access to a certain amount of crypto assets to conduct the transaction. Be sure to read the risks and benefits of token approvals .
- Follow the guide to approve spending the token. You must first sign a message to make the token available, and then sign a message to make the exchange. Both actions require a connected and unlocked Ledger device.
Step 5: Change network fees if necessary
The Ledger Live app allows you to set the appropriate network fees . Higher fees will result in a quick transaction confirmation, while lower fees may result in a slow transaction or even a cancellation. Read more…
- After selecting an operator, click on the arrow (>) to go to the network fees menu.
- The standard network fee menu allows you to choose between slow, medium and fast transaction confirmation. Choose any option that suits you.
- If you wish, you can open the advanced settings menu and set a custom commission in Gwei.
- Click Continue after setting the fees.
Step 6. Sign the exchange transaction
- Please check the transaction details carefully, including the current rate, network fees and maximum slippage.
- Sign the procedure and confirm the exchange using your Ledger hardware wallet.
The tokens will then be exchanged and forwarded to the desired blockchain. The transaction time depends on the chosen exchange route and network load.
What Do Blockchain Bridges Mean For The Future?
For a fluid blockchain future, interoperability is not only important – it’s a necessity. Being able to work and move assets across networks will be a driving force in the multi-chain future, from crypto networks to complexities with AI platforms.
Blockchain bridges represent a commitment to decentralization by enabling a truly interconnected ecosystem.
- For Users: Bridges simplify asset transfers and interactions across chains, reducing friction in digital transactions.
- For Developers: They unlock opportunities to build multi-chain dApps that combine the best features of various blockchains.
- For Businesses: Bridges enhance supply chain transparency, DeFi integration, and cross-platform operations.
In conclusion, blockchain bridges are not just tools for interoperability; they are foundational infrastructure for a decentralized digital economy.
By addressing security challenges (e.g., quantum threats), improving efficiency (adaptive routing), and nurturing innovation (multi-chain smart contracts), bridges will continue to shape the future of blockchain technology well beyond 2025.
Knowledge is Power.
Blockchain bridges are just one of the many ways developers have created to further the decentralization of the system as a whole – layer 2 blockchains are another important example. School of Block is here to check it out!