Decentralized finance and Web3 have grown exponentially on multiple blockchain networks like Ethereum, BNB Chain, Solana, and Avalanche. Each chain has strengths and tradeoffs in areas like scalability, decentralization, and tooling support.
This creates a dilemma for developers - which platform do you build on? Limiting a dApp to one chain cuts off liquidity and users on the rest. This has led to rising demand for multi-chain applications that work seamlessly across blockchain networks.
In this guide, we'll explore leading techniques to build dApps that provide unified experiences across multiple chains.
Why Build Multi-Chain dApps?
Here are the key benefits of a multi-chain architecture:
- Access More Users - Be usable no matter which chain users prefer or assets they hold.
- Expand Liquidity - Aggregate liquidity across isolated pools on each chain.
- Minimize Platform Risk - Reduce dependence on any one network's outages or policies.
- Leverage Strengths - Use the ideal chain for different operations - e.g. storage on Filecoin, computing on Solana.
- Future Proof - Position to support new emerging chains and shifts in user bases.
Just like modern web services are built cloud-native to scale across regions and platforms, multi-chain is the future for dApps aiming to maximize reach and liquidity.
Leading Approaches
There are two primary technical approaches to building multi-chain dApps:
Mirroring
Mirroring involves deploying the same smart contracts and user interface on each supported chain. The dApp logic and connectivity is replicated across networks.
For example, decentralized exchanges like PancakeSwap and Uniswap use mirrored implementations on BNB Chain and Ethereum respectively. Users can access the same DEX on both chains through chain-specific frontends.
Pros
- Simple to manage and build
- Native performance on each chain
Cons
- More expensive to deploy and maintain
- Stagnant feature parity across chains
- Fragmented liquidity and user bases
Bridges
Bridges enable a single backend dApp to work across chains by communicating between them. State and data is relayed cross-chain, so the dApp can operate as a unified whole on all integrated networks.
For example, the Qi DAO lending protocol uses the Wormhole bridge. This lets users lend assets on Solana or Ethereum through the same UI with aggregated liquidity.
Pros
- Single backend and frontend
- Shared liquidity and unified UX
- Easier feature development
Cons
- Requires more complex bridge infrastructure
- Some performance impacts from cross-chain relay
Example Bridges for Cross-Chain dApps
Here are some popular bridges used to develop multi-chain dApps:
- Wormhole - Solana and Ethereum bi-directional bridge from Jump. Allows arbitrary message passing.
- Celer cBridge - Supports Ethereum, BSC, Avalanche, Celo, and Polygon. Uses hash timelocks for security.
- Axelar - Supports 20+ chains. Uses Threshold Signatures and Proof of Authority for flexible bridging.
- Quantum Bridge - Provides L1 security to L2-to-L1 bridges by posting proofs to Ethereum
Bridges are maturing rapidly to support generalized communication between most major chains. This unlocks seamless multi-chain dApp development.
Building with Bridges
Developing with bridges involves:
- Deploying smart contract logic to each chain
- Integrating the bridge SDKs and libraries
- Managing bridge operations like approving token transfers
- Handling events when state updates arrive from other chains
Bridges abstract away the cryptography and network mechanics, exposing straightforward APIs. This enables dApps to harness cross-chain capabilities with minimal added complexity for developers.
Use Cases Showcasing Multi-Chain Utility
Here are some examples of innovative multi-chain dApps unlocking new utility by bridging siloed networks:
- Qi DAO - Lending protocol allowing collateral supplying on Ethereum and borrowing on Solana in a unified experience.
- Allbridge - Omni-directional asset bridge supporting Arbitrum, Avalanche, BNB Chain, Ethereum, Fantom, and Optimism.
- Mars Protocol - Yield aggregator that allows single-sided staking on one chain which is then used as collateral to borrow assets on another chain.
These demonstrate the creative possibilities multi-chain architectures enable - from shared liquidity to composability between DeFi ecosystems on each chain.
Conclusion
While Mirroring dApps across multiple chains is simpler, Bridges unlock superior user experiences and composability. As blockchain interoperability matures, users will come to expect the same seamless cross-chain capabilities from Web3 projects that they do from modern internet services.
Multi-chain with real-time connectivity between networks represents the next evolution of decentralized application development. Instead of competing, chains and their native platforms will form the building blocks of a coherent decentralized Web3.
