In the race to scale Ethereum
, optimistic rollups
have been the dominant force so far, with rollups such as Arbitrum
leading the layer two
(L2) space for most of 2022 up to, and through the Merge
(zk-rollups) represent the other side of the scaling race, utilizing zk-proofs
to overcome some of the fundamental downsides of optimistic rollups. While many, including Ethereum co-founder Vitalik Buterin
himself, regard zk-rollups as the future of Ethereum scaling, most live zk-rollups have largely flown under the radar. This is mainly because none of them have achieved much more than simple functions such as payments and trading. That is, until now.
Read: Optimistic Rollups vs ZK-Rollups: The Ultimate Comparison
The end of March saw a wave of developments in the zk-rollup space, or more specifically, the zero-knowledge Ethereum Virtual Machine
(zkEVM) space. These are chains that utilize zk-rollup technology while maintaining compatibility with the EVM.
Zk-rollups have long struggled with attaining EVM compatibility due to the design of the EVM which was not built with zk-proofs in mind. As such, the launch of the first two zkEVMs on their respective mainnets represent a huge step forward for the zk-rollup space.
Source: ZkSync Era Medium (link)
On March 24th, zkSync Era was launched to mainnet. Not long after, Polygon
launched their own Polygon zkEVM to mainnet on the subsequent Monday.
With all eyes on the two chains, it begs the question, what’s the difference between the two chains?
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Launched by blockchain research and engineering firm Matter Labs, zkSync Era has been many years in the making. Matter Labs released zkSync 1.0 (now zkSync Lite) in June 2020 and subsequently zkSync 2.0 in Q4 2022.
Source: Matter Labs website (link)
ZkSync Era is the culmination of years of research and development and the natural evolution of zkSync 2.0, to bring to life the very first zkEVM chain.
Polygon zkEVM is developed and released by Ethereum scaling company, Polygon. Polygon began their scaling journey with their proof-of-stake sidechain
, commonly referred to as the Polygon chain. Polygon was well-aware of the criticisms surrounding its sidechain, namely in terms of security and centralization.
Behind the scenes, they explored the zk-rollup space extensively, making large acquisitions of zk-related companies like Hermez and Mir, as well as developing collaborative projects such as Polygon Nightfall, Polygon Miden and Polygon Zero.
Source: Polygon Miden (link)
These efforts resulted in the launch we see today, with Polygon zkEVM being the combination of Polygon Hermez’s evolution and technological breakthroughs derived from work done on Polygon Zero.
Aside from the fact that both chains are zkEVM chains, both chains are also fully open-sourced
, true to the ethos of the crypto space. ZkSync Era’s code is licensed under the MIT/Apache 2.0 License. On the other hand, Polygon zkEVM is under the AGPL V3 license.
While both chains currently use Ethereum as their data availability
layer, both have data availability solutions as part of their product lines. Polygon has been developing Polygon Avail, which has recently been spun out of Polygon Labs as a standalone company helmed by Polygon co-founder, Anurag Arjun. Matter Labs has their own data availability product, zkPorter, which was announced in 2021. ZkPorter will be integrated into zkSync Era as an option for decentralized data availability later in their roadmap.
Source: Matter Labs (link)
Both zkSync Era and Polygon zkEVM also support account abstraction
, albeit in different ways. ZkSync Era supports it natively as they use their custom built VM. Polygon zkEVM, in a bid to preserve EVM equivalence, is unable to support account abstraction natively, but does so via Ethereum’s ERC-4337
Finally, on the security front, both chains currently do not have timelocks on their contracts, allowing instant upgradability. This is mainly to enable timely upgrades or fixes in the event of any bugs in their contracts as both are still in their early days. Polygon zkEVM, however, has a security council, requiring four of seven signers to enable any upgrades while zkSync Era currently runs without a security council although it has plans to implement one in the future.
Similarities aside, zkSync Era and Polygon zkEVM differ significantly under the hood.
The main difference between the two is that ZkSync Era is EVM compatible whereas Polygon zkEVM is EVM equivalent.
ZkSync Era uses its LLVM compiler, which compiles code from various popular EVM languages such as Solidity
, Vyper and Yul to run on their custom zkSync VM. This compiler will be further developed to accept code in Rust
in the future as well. This allows developers to migrate EVM smart contracts, instead of rewriting code using a new language or tool.
Polygon zkEVM, on the other hand, treads much closer to EVM and does not use a compiler. It accepts Solidity natively, enabling the migration of almost all Solidity code from existing EVM chains to the new chain without rewriting the code. Using Vitalik’s framework
for the different types of zkEVMs, zkSync Era is closer to a Type 4 zkEVM, while Polygon zkEVM is a Type 3 zkEVM, with the intention to progress to a Type 2 zkEVM.
Source: Vitalik Buterin (link)
Looking to prover architecture, zkSync Era aims for quicker proof generation by optimizing using their custom VM, instead of aiming for EVM equivalence. Polygon zkEVM uses a unique Proof-of-Efficiency consensus mechanism
in conjunction with a cluster of state machines
which enables greater prover efficiency.
In terms of data availability, ZkSync Era only publishes state diffs rather than transaction inputs
, providing data compression as well as seamless integration with zkPorter. This is based on the Volition model by StarkWare, although ZkSync has adapted it for “strict focus on decentralization.” Meanwhile, Polygon zkEVM will use a hybrid model (either Validium or Volition) where validity proofs are stored on-chain, while some data is stored on or off-chain.
Thus far, zkSync Era has amassed a whopping $100 million in total value locked
since their launch just over a week ago. This is significantly higher than the $2.2 million on the Polygon zkEVM chain.
Source: L2Beat (zkSync Era TVL)
Source: L2Beat (Polygon zkEVM TVL)
Some have speculated that this discrepancy is largely due to the airdrop
potential on zkSync Era. With the launch of zkSync Era, just a day after Arbitrum’s airdrop
opened up for claims, airdrop hunters are on the prowl again for their next target. ZkSync Era is one of the prime targets, with Matter Labs having raised $458 million in funding over the years.
That said, Matter Labs CEO, Alex Gluchowski, has openly stated in an interview
that zkSync Era has currently no need for a token, although he did add that a token will be required for the eventual decentralization of the chain.
On the Polygon front, the team has clarified that Polygon zkEVM will not have its own token, although hinting that the MATIC token will be used for staking
on Polygon zkEVM in the future.
That said, both chains are still in their early days and both have secured partnerships with huge decentralized applications
(DApps) such as Sushi
, and more. With the deployment of these major DApps upcoming, we could see another spike in new users on these zkEVMs.
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