Choosing between Optimistic Rollup and ZK Rollup for your project depends on several factors, such as your scalability needs, security preferences, latency tolerance, privacy requirements, validity proof method, readiness for DeFi, and programming easiness. Here are some general guidelines to help you decide:
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If you need high scalability and low costs, and you are willing to sacrifice some security and finality, you may prefer Optimistic Rollup. Optimistic Rollup can support higher transaction volume and lower fees than ZK Rollup, because it does not need to generate or verify zero-knowledge proofs. However, Optimistic Rollup relies on fraud proofs and challenge periods to ensure the validity of transactions, which means that it is vulnerable to attacks or errors during the waiting period.
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If you need high security and fast finality, and you are willing to sacrifice some scalability and costs, you may prefer ZK Rollup. ZK Rollup uses zero-knowledge proofs to prove the validity of transactions instantly on Layer 1, without revealing any details about them. This means that ZK Rollup can offer higher security and faster finality than Optimistic Rollup, but it requires more computation and data on Layer 2.
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If you need low latency and instant withdrawals, you may prefer ZK Rollup. ZK Rollup does not require a waiting period to exit Layer 2 to Layer 1, unlike Optimistic Rollup. This means that ZK Rollup can offer lower latency and instant withdrawals than Optimistic Rollup, which can improve the user experience and liquidity.
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If you need privacy and anonymity, you may prefer ZK Rollup. ZK Rollup uses zero-knowledge proofs to hide the details of transactions from third parties, while still proving their validity. This means that ZK Rollup can offer more privacy and anonymity than Optimistic Rollup, which exposes the transaction data on Layer 2.
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If you need validity proof by construction, you may prefer ZK Rollup. ZK Rollup uses validity proofs to ensure the validity of transactions on Layer 2, without relying on any assumptions or challenges. This means that ZK Rollup can offer validity proof by construction, which is more robust and reliable than Optimistic Rollup’s fraud-proof scheme.
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If you need readiness for DeFi, you may prefer Optimistic Rollup. Optimistic Rollup is fully compatible with the Ethereum Virtual Machine (EVM), which means that any smart contract or dapp that runs on Ethereum can run on Optimistic Rollup without any changes. This means that Optimistic Rollup can support more DeFi applications and composability than ZK Rollup, which is not fully compatible with the EVM.
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If you need programming easiness, you may prefer Optimistic Rollup. Optimistic Rollup allows developers to use the same tools and languages that they are familiar with on Ethereum, such as Solidity and Remix. This means that Optimistic Rollup can offer more programming easiness than ZK Rollup, which requires developers to learn new tools and languages, such as Cairo and StarkNet.
Of course, these are not absolute rules, but rather general suggestions based on the current state of the technology. Both Optimistic Rollup and ZK Rollup have their advantages and disadvantages, and they are suitable for different use cases and preferences. Some examples of projects that use Optimistic Rollup are Uniswap V3, Synthetix, Arbitrum, and [Optimism]. Some examples of projects that use ZK Rollup are [Loopring], [Immutable X], [zkSync], and [StarkWare].