What Are Blockchain Bridges For?

What Are Blockchain Bridges For?

Interoperability between blockchains is crucial for the growth of the crypto industry, and blockchain bridges are a protocol designed to enable it. These bridges connect two separate blockchains, allowing for seamless interaction between them.

With a blockchain bridge, users can utilize different blockchain networks without having to liquidate their assets. For example, if a user owns bitcoin but wishes to participate in DeFi activities on the Ethereum network, a blockchain bridge can facilitate this process. Ultimately, blockchain bridges play a key role in achieving a more connected and integrated blockchain ecosystem.


Blockchain ecosystems such as Bitcoin and Ethereum have different consensus protocols, programming languages, and system rules. A blockchain bridge, a protocol connecting two separate blockchains, enables interoperability between them, similar to a physical bridge linking two islands. Interoperability is crucial in enabling digital assets and data on one blockchain to interact with another, allowing for an easy exchange of data and value. In the blockchain space, where there are numerous distinct protocols, blockchain bridges are essential to achieving the ease of exchanging data and value similar to that of the internet.

What Are Blockchain Bridges For?

The blockchain industry has faced a significant hurdle in its development and expansion - the inability of different blockchains to work together due to varying rules, tokens, protocols, and smart contracts. This has created silos that have hindered the growth of the industry. Blockchain bridges aim to break down these silos and connect different blockchain ecosystems. By interconnecting blockchains, tokens and data can be exchanged smoothly, allowing for an interconnected network of blockchains.

In addition to facilitating cross-chain transfers, blockchain bridges have other benefits. They allow users to access new protocols on other chains and enable developers from different blockchain communities to collaborate. Thus, blockchain bridges play a critical role in achieving an interoperable future for the blockchain industry.

How Do Blockchain Bridges Work?

By using a blockchain bridge, it's possible to transfer tokens from one blockchain network to another without selling your crypto. For example, if you have Bitcoin (BTC) but want to use it on the Ethereum network, you can use a blockchain bridge to wrap it into an ERC20 token called Wrapped BTC (WBTC).

To do this, a smart contract will lock your BTC and mint an equivalent amount of WBTC. WBTC is a tokenized version of BTC that's pegged to its value and can be redeemed for it at any time.

To use a blockchain bridge, you'll need to select the chain you'd like to bridge from and specify the amount you want to transfer. Then, you'll need to deposit your crypto to an address generated by the bridge. After the crypto is sent to the address during the time window, the bridge will send you an equivalent amount of wrapped tokens on the other blockchain. If you want to convert your funds back, you can simply go through the reverse process. A token transfer is the most common use case for blockchain bridges, and they provide many benefits, including lower fees and reduced price volatility.

Types of Blockchain Bridges

There are different ways to categorize blockchain bridges based on their functions, mechanisms, and levels of centralization.

Custodial vs. Non-Custodial Bridges

One common way to classify bridges is as custodial (centralized) or non-custodial (decentralized) bridges.

Custodial bridges require users to trust a central entity to properly operate the system, which could raise concerns about security and privacy. Users are advised to conduct thorough research to ensure the trustworthiness of the entity.

On the other hand, non-custodial bridges operate in a decentralized manner and rely on smart contracts to manage the crypto-locking and minting processes. These bridges eliminate the need to trust a central entity, and the security of the system depends on the code underlying the smart contracts.

Bridges by Functions

The different types of blockchain bridges can be categorized based on their functions. Two examples of these are the wrapped asset bridges and the sidechain bridges. Wrapped asset bridges facilitate the interoperability of cryptocurrencies by wrapping them to be compatible with a different blockchain. For instance, the WBTC enables Bitcoin to be used in the Ethereum ecosystem by wrapping BTC into an ERC20 token.

Meanwhile, sidechain bridges connect a blockchain to its child sidechain to enable interoperability between them, even when they have different consensus mechanisms. The xDai Bridge is an example of a sidechain bridge that connects Ethereum to the Gnosis Chain. By doing so, xDai enables the transfer of value between the two networks even though they are secured by different validators.

Bridges by Mechanisms

Blockchain bridges can be classified based on the direction of asset transfer they enable. A one-way bridge only allows users to move assets from one blockchain to another, but not back to its native blockchain. On the other hand, a two-way bridge allows bidirectional asset bridging, meaning users can move assets between two blockchains in both directions.

Benefits of Blockchain Bridges

Blockchain bridges are a critical component that can enhance interoperability and scalability in the blockchain industry. Their primary function is to enable the exchange of tokens, assets, and data across different blockchains, whether between layer 1 and layer 2 protocols or various sidechains. Interoperable blockchains are essential for the industry's future success. For example, Wrapped BTC enables bitcoin users to access decentralized applications and DeFi services in the Ethereum ecosystem.

Apart from enhancing interoperability, blockchain bridges can improve scalability in the blockchain industry. Some blockchain bridges can handle a large volume of transactions, making the process more efficient. An example is the Ethereum-Polygon Bridge, which is a decentralized two-way bridge that serves as a scaling solution to the Ethereum network. This way, users can benefit from faster transactions and lower transaction costs.

Disadvantages of Blockchain Bridges

The use of blockchain bridges comes with some limitations and potential risks. For instance, smart contract vulnerabilities in some blockchain bridges have been exploited by attackers, leading to the misappropriation of a large amount of crypto across different blockchains.

Additionally, custodial bridges may expose users to custodial risks, with the potential for the centralized entity behind the bridge to steal users' funds. To mitigate this risk, it is advisable to use established brands with a long-term track record. Transaction rate bottlenecks could also hinder large-scale blockchain interoperability, as a single chain's throughput capacity bottleneck could limit the speed of transactions.

While blockchain bridges can alleviate congestion on a busy network, moving assets away to another chain does not necessarily solve the scalability issue, as users may not have access to the same suite of dapps and services. Furthermore, blockchain bridges can expose the underlying protocols to risks related to the disparity in trust. Since blockchain bridges connect different blockchains, the overall security of the interconnected networks is only as strong as the weakest link.

The Future of Blockchain Bridges

Blockchain bridges are crucial for achieving interoperability and expanding the adoption of blockchain technology. They have revolutionized the industry by enabling the exchange of assets and data between various blockchain protocols. As a result, the number of bridges, users, and transaction volume has grown significantly.

As the internet moves towards Web3, the need for blockchain bridges is likely to increase. Innovations in the future may provide greater efficiency and scalability for users and developers. Additionally, new solutions may emerge to address the security risks associated with bridges.

Blockchain bridges play a critical role in creating an open and decentralized blockchain ecosystem. They are essential for the industry's continued growth and success.


The blockchain industry thrives on innovation, with the introduction of various protocols, including pioneers like Bitcoin and Ethereum, followed by alternative layer 1 and layer 2 blockchains. The number of crypto coins and tokens has increased exponentially, necessitating the need for blockchain bridges to interconnect them. Blockchain bridges create a more cohesive and interoperable ecosystem that promotes scalability and efficiency. However, numerous attacks on cross-chain bridges highlight the need for more secure and robust bridge designs.

Blockchain Bridges
Crypto Bridges
Custodial Bridges
Non-Custodial Bridges