What are Bitcoin Bridges?

General Wallet Use

15 min

As more blockchains emerge and the crypto community grows, cross-chain interoperability has become more of a demand. Having diverse holdings of different crypto tokens can be very complicated and tedious when every chain is an isolated system. 

Without crypto bridges, a type of interoperability mechanism, exchanging different cryptos can be nearly impossible and requires a third-party. This usually means a centralized exchange — which defeats the purpose of decentralized finance (DeFi). Here’s what bridges do for DeFi and how they work.

What are Cross-Chain Bridges?

Cross-chain bridges are becoming more important in an increasingly interoperable crypto world. Bridges are protocols that allow data or crypto tokens to be exchanged between different blockchains. 

For example, a bridge could allow BTC to be ported to the Ethereum blockchain by locking or burning BTC on the Bitcoin chain and minting tokens on Ethereum. Without bridges, each blockchain operates in a silo. Tokens created on a chain stay on that chain. 

Bridges are like connectors, allowing interoperability and communication between separate blockchain protocols. Some typical types of bridges are:

  • Trusted bridges — requiring a trusted third party.

  • Trustless bridges —direct, P2P using smart contracts.

  • Unidirectional bridges — bridging only in one direction from chain A to chain B.

  • Bidirectional bridges — allowing assets to be exchanged in both directions between blockchains.

As an integrated, multi-chain ecosystem becomes more desirable for builders and users, bridges will continue to become more important. Moving digital assets like Bitcoin or NFTs between different blockchains would be entirely too complicated without bridges. They streamline the process, eliminating the need for centralized exchanges.

Some reasons you might use a cross-chain bridge include:

  • Speed — A user may want to use their assets on a blockchain that completes transactions faster.

  • Cost — Some blockchains have higher fees than others, bridging to save on gas fees can help.

  • Asset diversity — If you need native tokens on another blockchain, bridges are useful.

  • Interaction variety — some platforms and markets are only available on certain blockchains, creating the need to move tokens to the desired chain.

Bridges expand the possibilities for user features on different networks, and reduce the need for multiple wallets and accounts. They also improve scalability. These attributes make cross-chain bridges very important for decentralized finance.

Although cross-chain bridges offer greater utility, there are also potential risks. Some bridges, for example, require custody during bridging. This means users must entrust a third party their assets, which eliminates the benefit of trustless, peer-to-peer swapping.

Non-custodial bridges, on the other hand, rely completely on smart contracts. This introduces other risks. Potential for bugs within the code exists, creating the opportunity for protocol failure or hacking and exploits. 

What are Bitcoin Bridges?

Bitcoin bridges have many similar functions to cross-chain bridges, but they also have unique attributes. Unlike some other blockchains, Bitcoin has programmability and throughput capacity limitations. These characteristics offer unparalleled security, but they can hamper cross-chain compatibility. Therefore, bridges are implemented differently on the Bitcoin blockchain.

Bitcoin bridges often rely on layers to overcome the chain's throughput capacity bottleneck. Layer-2 (L2) solutions like Lightning, RSK, Stacks, or Liquid are some examples. These L2 solutions resolve transactions off-chain, enabling more varied functionality. They also enable Bitcoin bridges to handle transactions at a much larger scale than the mainchain alone.

Over time, the technical limitations of the Bitcoin blockchain have generated very creative and adaptive solutions. And each of these innovations have led to more and better Bitcoin functionality.

Examples of Bitcoin Bridges

  • RSK (RBTC) — A sidechain specifically designed to enhance the scalability of Bitcoin. It allows for the creation of Bitcoin-based decentralized applications (dApps).

  • tBTC — A trust-minimized bridge between the Bitcoin and Ethereum blockchains. tBTC is a Bitcoin-equivalent asset minted and used to interact with Ethereum dApps.

  • Avalanche Bridge — This bridge facilitates the transfer of BTC from Bitcoin to Avalanche's C-Chain.

  • Polkadot Bridge — A two-way bridge between the Polkadot and Bitcoin blockchains, allowing sending and receiving BTC for iBTC on Polkadot.

One of the loudest criticisms of the Bitcoin blockchain has been its limited functionality. While Bitcoin is the oldest and largest blockchain, those features tend to come at the cost of speed and interoperability.

However, Bitcoin bridges are creating new and exciting ways for Bitcoin holders to interact with DeFi and other dApps. This allows a richer experience and the chance to explore a broader range of financial instruments. 

Cross-chain compatibility not only enhances the overall utility of Bitcoin, but it contributes to the depth of the DeFi landscape overall. As crypto investors and technology builders become more sophisticated, new functionalities created by bridges are crucial.

How Do Bitcoin Bridges Work with Bitcoin Wallets?

In order to obtain tokens or interact with any blockchain, users need crypto wallets. And wallets are also important when using cross-chain bridges. Without exchanges and bridges, you would need a different wallet for every different token you owned.

One of the best types of wallets for using bridges are self-custody wallets. Sometimes called non-custodial wallets, they align with the principles of decentralization and crypto. Both software wallets like MetaMask and hardware wallets like Ledger or Trezor can work with cross-chain bridges. 

As with everything in crypto, new protocols and platforms tend to pose new threats. Using bridges with your crypto wallet is no exception. Be sure to understand potential security concerns, particularly when using bridges that involve custody of assets by third parties. 

Trusted bridges, in particular, may require users to give up control of their assets during the bridging process. This creates a significant risk if the custodial entity faces vulnerabilities. For trustless bridges — make sure to minimize the possibilities for user error, accidental transactions, and potential code errors.

Trustless bridges are intended to mitigate custody risks by operating solely on smart contracts and algorithms. This and other developments are always working to shore up vulnerabilities. But it’s always important to interact carefully and safely with dApps and protocols. 


If you’re getting involved with DeFi and trying different platforms, technologies, and markets, get yourself a Leather wallet. Our non-custodial Bitcoin wallet will give you the flexibility you need to access all your assets.

Connect to web3 applications built on Bitcoin with the Leather browser extension. Install Leather – the only wallet you need to tap into the multilayered Bitcoin economy – today.