Web3 has dealt with an intractable scaling problem for its entire history. Although developers continue cranking out new chains to keep pace with the growing demand for block space on Ethereum, it comes with the cost of poor UX and fragmented liquidity.&nbsp;Thankfully, Layer-2 solutions have muscled to the forefront of improved scalability—primarily via transaction throughput with the benefits of reduced gas fees.Zero-Knowledge Rollups (ZK-Rollups) are one such Layer-2 solution. They improve Ethereum's scalability by moving computation and state off-chain to alleviate some of the load on Layer 1. But ZK-Rollups can be challenging for developers to adopt because of their custom Virtual Machines (VMs). So, what is the next evolutionary phase for ZK-Rollups?&nbsp;<figure class="image"><img src="https://tidy-ball-c49dc59f59.media.strapiapp.com/data_scalability_problem_e1a6aa4024.jpeg" alt="data_scalability_problem.jpeg"><figcaption>The Data Availability Bottleneck - source <a target="_blank" rel="noopener noreferrer" href="https://inevitableeth.com/home/ethereum/upgrades/scaling/data/data-availability-bottleneck">inevitableeth.com</a></figcaption></figure><h2>zkEVMs to the Rescue</h2>The Ethereum Virtual Machine (EVM) is Ethereum's computation engine that manages the blockchain state and enables smart contract functionality. Therefore, Layer-2 solutions that can accomplish EVM compatibility provide the foundation for significant advancements in scalability. That's because developers who already know how to program in Solidity can jump into building on Layer-2 with the same tools they're used to.Zero-Knowledge Ethereum Virtual Machine (zkEVM) is the latest advancement in ZK-Rollups. zkEVMs enable ZK-Rollups to become EVM compatible and more general purpose than strictly application specific. In other words, developers can build whatever they usually would on Ethereum while taking advantage of the benefits of ZK-Rollups.zkEVM is a virtual machine that executes smart contract transactions while staying compatible with ZK-Proof computations and the Ethereum infrastructure. This evolutionary step is not surprising since Ethereum co-founder, Vitalik Buterin predicted in 2021 that ZK Rollups, with their inherent advantages, would eventually out-compete Optimistic Rollups.<img src="https://tidy-ball-c49dc59f59.media.strapiapp.com/rollups_29b0a9df4b.png" alt="rollups.png">As it stands, the Optimistic Rollups Arbitrum One and OP Mainnet dominate market share in TVL with 50% and 25%, respectively, while top ZK-Rollup projects zkSync Era and dYdX v3 lag far behind at 2.5% and 1.5% (according to L2Beat). However, this incredible zkEVM technology could finally put ZK-Rollups on a direct path to challenge Optimistic Rollups' dominance.So, while the battle to better scale Ethereum has heretofore been waged between Optimistic and ZK-Rollups, a new friendly competition has emerged between the different zkEVMs offerings. This competition is a race to determine who can create a Type-1 or Type-2 zkEVM solution first. Before we examine some zkEVM projects, let's look at the difference between EVM compatibility and equivalence. Then, we can better distinguish the various types based on <a target="_blank" rel="noopener noreferrer" href="https://vitalik.eth.limo/general/2022/08/04/zkevm.html">Vitalik's zkEVM classifications,</a> as seen below.&nbsp;<h2>EVM Compatibility vs. Equivalence</h2>Attaining EVM compatibility means the zkEVM is compatible with Ethereum, but it is not the same developer experience. Developers working with this type of zkEVM may still need to rewrite some smart contracts.EVM equivalence means that any smart contract or developer tool from the Ethereum Layer-1 ecosystem will also work on the zkEVM network. It's almost the same as Ethereum.&nbsp;&nbsp;<h2>zkEVM Types</h2><figure class="image"><img src="https://tidy-ball-c49dc59f59.media.strapiapp.com/vitalik_zk_EVM_classifications_aaed5e860c.png" alt="vitalik_zkEVM_classifications.png"><figcaption>Vitalik's zkEVM classifications</figcaption></figure><h3>&nbsp;</h3><h3>Type 1 - Fully Ethereum Equivalent&nbsp;</h3>With Type-1 zkEVMs, all Solidity smart contracts and developer tools will work flawlessly. Type 1 is ideal as it accomplishes equivalence with Ethereum. However, purity has its price—the most extended Prover times of all the types.Pros:<ul><li>&nbsp;Perfect Ethereum equivalence&nbsp;</li><li>&nbsp;Long-term scalability</li></ul>Cons:<ul><li>Lengthy Prover time</li></ul>&nbsp;<h3>Type 2 - Fully EVM Equivalent</h3>This type of zkEVM strikes a balance between EVM and Ethereum equivalence with faster Prover times than Type 1. While Type 1s try to be equivalent with the entirety of Ethereum, Type 2s only try to be equivalent within the EVM. So, most developer tools will also work in this environment. However, some modifications will persist because of the inherent "ZK-unfriendly" design in the EVM itself.Pros:<ul><li>Excellent compatibility with Ethereum dApps</li><li>Better Prover times than Type 1</li></ul>Cons:<ul><li>Some modifications might be necessary</li></ul>&nbsp;<h3>Type 2.5 - EVM Equivalent</h3>This type tackles worst-case Prover times. It does so by increasing the gas costs to disincentive the use of specific EVM operations that are difficult to ZK-prove. So, it's similar to Type 2, but Prover times are improved by increasing transaction fees.Pros:<ul><li>Improves the worst-case Prover times</li></ul>Cons:<ul><li>Reduced compatibility with specific dApps</li><li>Hard gas limits can be inflexible</li></ul>&nbsp;<h3>Type 3 - Almost EVM Equivalent</h3>The advantage of Type 3 zkEVMs is they're easier to build, and Prover times are faster. Type 3's make some compromises to speed up Prover times, however. Thus, they may need to remove features they deem challenging to implement. zkEVM projects typically consider the Type-3 stage merely transitional while working towards becoming Type 2.Pros:<ul><li>Faster prover times and easier to develop</li><li>Compatibility with most dApps</li></ul>Cons:<ul><li>Some dApps may require rewriting</li><li>Not fully EVM-equivalent</li></ul>&nbsp;<h3>Type 4 - High-Level Language Equivalent</h3>This type of zkEVM takes a different approach. Type 4s take smart contract source code (written in high-level languages like Solidity) and compile it to a language that is easier to ZK-prove. This approach can lead to quick Prover times but requires much developer work in debugging and maintenance to overcome inherent incompatibilities with specific dApps.Pros:<ul><li>Hyper-fast Prover times</li></ul>Cons:<ul><li>Incompatibility issues with specific dApps</li></ul>In sum, as you move from Type 1 to Type 4, you start with the slowest Prover times but the most compatibility with Ethereum. Moving down to Type 4, you get the fastest Prover times but the least compatibility with Ethereum.Based on these types, it's evident that different zkEVM projects bring their unique blend of performance and compatibility. Furthermore, depending on project requirements, one type may be preferable to another.All in all, developers can make better choices for their projects by understanding the trade-offs of each zkEVM type. Now, we're ready to look at some zkEVM projects making a splash in the Layer-2 ecosystem.&nbsp;<h2>Introducing Polygon 2.0</h2>Polygon embraces the ethos of experimentation. So, rather than dogmatically sticking to a single approach when tackling Web3's scalability problem, its team explored multiple paths, such as sidechains, rollups, and validiums.After learning some important lessons, the team began consolidating their ideas and efforts into building a unified multichain ecosystem called <a target="_blank" rel="noopener noreferrer" href="https://www.luganodes.com/blog/Polygon2Ecosystem/?utm_source=Blog&amp;utm_medium=article&amp;utm_campaign=Blog%20-%20article%20-%20zkEVMforStakingRewards">Polygon 2.0</a>.The vision for 2.0 is a carefully crafted web of ZK-powered Layer-2 solutions with near-instant transactions—a place where developers can create without limitations.Within this 2.0 mix resides Polygon zkEVM, an offshoot of the team's technological breakthroughs while building Polygon Hermez and Polygon Zero.<a target="_blank" rel="noopener noreferrer" href="https://www.luganodes.com/blog/MATICSG/">Stake your Polygon $Matic tokens with Luganodes</a> and start earning passive income today!&nbsp;<h2>What Is Polygon zkEVM?</h2>Polygon zkEVM is an EVM-compatible ZK-Rollup scaling solution. It uses ZK proofs to increase throughput and lower transaction costs while inheriting Ethereum's base-layer security. Most importantly for developers, nearly everything you can do on Ethereum (except for edge cases) you can do on <a target="_blank" rel="noopener noreferrer" href="https://polygon.technology/polygon-zkevm">Polygon zkEVM</a>. Most developer tools, wallets, and existing smart contracts work seamlessly with it, so developers don't have to worry about using special tools or rewriting code.Under the hood is a different story, however. The Polygon team pulled quite an engineering feat to get their EVM's opcodes to match Ethereum's. But they were determined to deal with the complexity so users wouldn't have to, and they've created a stack that any developer who codes in Solidity can come in and build on top of.&nbsp;<h2>What Is zkSync Era and Hyperchains?</h2>The team at Matter Labs brings us zkSync Era, which consists of a network of Hyperchains. These Hyperchains are ZK-powered, modular blockchains that operate on top of their Layer 2 and offer near-instant liquidity transfers between protocols in the system.zkSync describes them as "fractal-like instances of zkEVM" that run parallel with the settlement on the Layer-1 mainnet. A network of fully trustless Hyperbridges keeps these Hyperchains interconnected, which enables fast, trustless, and low cost-per-transaction interoperability. The concept of Hyperbridges does away with the need for insecure token bridges—a consummate weak point so often exploited by hackers.<img src="https://tidy-ball-c49dc59f59.media.strapiapp.com/shared_bridge_layer1_ETH_5d7644c734.png" alt="shared_bridge_layer1_ETH.png">&nbsp;<h2>Hyperchains in the ZK Stack</h2>ZK Stack is the framework for building <a target="_blank" rel="noopener noreferrer" href="https://era.zksync.io/docs/reference/concepts/hyperscaling.html#scaling-blockchains">Hyperchains</a>; anyone can develop and deploy their own chain. The good news for developers/creators is they keep full rights to the code with unfettered autonomy to customize every aspect of the chain as they see fit. However, for those building generic dApps, deploying on an existing Hyperchain is the easiest way to go.More features are listed below:<ol><li>ComposableHyperchains can seamlessly connect in a trustless network.</li><li>ModularUsing the ZK Stack, developers can customize every aspect of their Hyperchain, including data availability mode, choice of sequencer, and tokenomics.</li><li>Layer-1 SecurityHyperchains inherit their security from Layer 1. &nbsp;</li><li>No Hard ForksLayer 1 is the single source of truth. Therefore, the rollups cannot hard fork. However, the ecosystem as a whole can hard fork if necessary, similar to how the L1 would react to a vulnerability.</li><li>Battle-tested&nbsp;zkSync Era stands on its security track record as the most adopted ZK-Rollup regarding TVL and transaction volume.</li></ol>While the ZK Stack could theoretically connect to other ZK-Rollups like Polygon's zkEVM, this type of interoperability between rollup solutions isn't likely to happen soon.&nbsp;<h2>Comparing zkSync Era and Polygon zkEVM</h2>zkSync and Polygon have open-source zkEVM chains. They also use Ethereum as their data availability layer. However, Polygon zkEVM and zkSync Era are different under the hood. Namely, Polygon zkEVM is EVM equivalent, and zkSync Era is EVM compatible.So, instead of aiming for EVM equivalence, zkSync Era aims for quicker proof generation with its custom VM. It compiles code from various EVM languages like Solidity and Vyper to run on its custom VM.Polygon zkEVM, on the other hand, does not use a compiler. It enables nearly all Solidity code to migrate to its new chain without rewriting. Polygon aims for a closer alignment with Ethereum, while zkSync Era allows for some deviations. Hence, zkSync Era is more relative to a Type 4, while Polygon zkEVM is a Type 3, intending to progress to a Type 2 zkEVM.&nbsp;<h2>Comparing Other zkEVM Projects</h2>As mentioned, Polygon zkEVM is currently a Type 3, working to be a Type 2. That means some differences in opcodes, precompiled smart contracts, and other minor issues need patching to reach that Type 2 status.However, other zkEVM projects are taking different approaches. Typically, the differences boil down to how equivalent they want to be with Ethereum or the EVM. Some projects need special tooling or particular compilers to work with the EVM, while others opt for solutions incompatible with Ethereum.<img src="https://tidy-ball-c49dc59f59.media.strapiapp.com/zk_EV_Mlandscape_min_1_2cbc3f2c2e.png" alt="zkEVMlandscape-min (1).png">&nbsp;Taiko claims to be a fully Ethereum equivalent Type 1 zkEVM currently in the testnet phase. Another contender, Linea, started as a Type 3 zkEVM but is already calling itself Type 2 with claims of being fully bytecode compatible. It's a new entry by <a target="_blank" rel="noopener noreferrer" href="https://consensys.io/">Consensys</a> (which also powers Metamask, Infura, and Truffle). What sets Linea apart is Consensys' reputation, which has helped Line forge strategic partnerships.&nbsp; &nbsp;Scroll is another Type 3 working towards Type-2 status. Since it went live on mainnet back in october 2023, it has attracted <a target="_blank" rel="noopener noreferrer" href="https://x.com/Scroll_ZKP/status/1747842195141611669?s=20">more developers in 2023 Q3 than most other ecosystems</a>.&nbsp;<h2>What Is Polygon CDK?</h2>But we're not through with Polygon yet. It also offers the Polygon CDK (Chain Development Kit), which is the firm's toolkit for developers looking to design and launch ZK-powered chains. With its cryptographic security, it attains transaction integrity without needing full nodes. This benefit guarantees robust security and near-instant finality.The software components in Polygon CDK are open-source and modular. So, a chain can use any part of the stack it needs and discard what it doesn't need. In this environment, developers can launch ZK-powered chains or transition existing Layer-1 chains into Layer 2s.With EVM-equivalence, developers won't need to rewrite code. And on the horizon comes seamless interoperability with the other Layer 2s in the Polygon ecosystem. This includes its side chain, Polygon PoS, and the ZK-Rollup network mentioned earlier —Polygon zkEVM.&nbsp;<h2>zkEVM Supremacy</h2>The Ethereum community embraces the idea of ZK-Rollups becoming the preeminent Layer-2 scaling solution based on Vitalik's predictions. But it wasn't until recently that the concept of a general-purpose zkEVM running all Ethereum dApps became possible.The push to Type 2 zkEVM offers developers and users significant UX enhancements and a new frontier of possibilities. With so many great teams pushing for a Type-2 status (or even Type-1), how long can Optimistic Rollups hang onto their dominant position in the Layer-2 solution space?Check out the new frontiers of possibilities with staking at <a target="_blank" rel="noopener noreferrer" href="https://www.stakingrewards.com/provider/luganodes">Luganodes</a>!&nbsp;Author: LuganodesAbout LuganodesLuganodes is a world-class, Swiss-operated, non-custodial blockchain infrastructure provider that has rapidly gained recognition in the industry for offering institutional-grade services. It was born out of the Lugano Plan B Program, an initiative driven by Tether and the City of Lugano. Luganodes maintains an exceptional 99.9% uptime with round-the-clock monitoring by SRE experts. With support for 30+ PoS networks, it ranks among the top validators on Polygon, Polkadot, Sui, and Tron. Luganodes prioritizes security and compliance, holding the distinction of being one of the first staking providers to adhere to all SOC 2 Type II, GDPR, and ISO 27001 standards. &nbsp;

Comparing zkEVM Layer-2 Solutions

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