The Four Major L2 Protocols of zk: Progress, Similarities and Differences, and Ecosystem

Author: Nianqing, ChainCatcher

Recently, with the launch of zkSync 2.0, zk scaling solutions have entered a new wave of excitement. Additionally, after last month's Devcon in Bogotá, many "new" voices have emerged in the zkEVM space.

For instance, zkSync has heavily promoted itself as "the world's first fully functional open-source zkEVM network." However, critics, including Steven Goldfeder, co-founder and CEO of Arbitrum development company OffChain Labs, have pointed out that this zkEVM testnet has not enabled zk-proofs and has not undergone a security audit, arguing that such promotion benefits no one and that there is still a long way to go before true implementation.

During the Bogotá Devcon, Polygon zkEVM also claimed to be "the first and only decentralized zkEVM testnet," but quickly faced community criticism: while the source code for Polygon zkEVM provers is available on GitHub, it does not yet have an open-source license; although it claims to be "fully equivalent," its GitHub repository shows that it has only achieved 97% compatibility coverage so far. In response, the Polygon team stated, "There is no deliberate concealment; some content is being documented better."

Moreover, Scroll announced a Pre-Alpha testnet upgrade during the Bogotá Devcon and opened testing to whitelisted users. According to plans, StarkWare launched an upgraded version of Cairo, Cairo 1.0, at the end of September, which is also expected to be officially released by the end of the year.

Stimulated by the Aptos airdrop, the strong narrative around L2 zk solutions has indeed attracted a large number of users. However, compared to the relatively mature op scaling solutions, zk solutions may seem bustling on the surface but are still far from true prosperity; the current ecosystem is relatively weak, and the development cycle for zk technology is longer, posing certain barriers for developers and projects. Therefore, rather than arguing over who is the "first zkEVM," it is better to continue building.

This article summarizes the development progress and ecosystem details of the four major zk protocols: StarkWare, zkSync, Polygon zkEVM, and Scroll, providing a comprehensive understanding of the current state of the hot zkEVM track.

1. Starkware

1. Introduction:

StarkWare is the project with the strongest team in the zk scaling solutions space. Co-founder Eli Ben-Sasson is a world-class cryptographic scientist and a co-inventor of zkSNARK and zkSTARK. Co-founder and CEO Uri Kolodny graduated from the Hebrew University with a degree in computer science and is also a serial entrepreneur. StarkWare is currently valued at $8 billion.

StarkWare has developed two products: StarkEx for ToB and StarkNet for ToC. StarkEx is an independent permissioned Validity-Rollup, selling customized technology engine services and charging service fees directly to clients with scaling needs. It currently serves clients such as dYdX, ImmutableX, Sorare, DeversiFi, rhino.fi, ApeX, and Myria. StarkNet is a permissionless decentralized zk-Rollup open to everyone, using the zkSTARK proof system and supporting dApp self-deployment.

The underlying smart contract language used by StarkNet is not Solidity but Cairo, a Turing-complete zero-knowledge proof system language that is not compatible with EVM. The team has been seeking zkEVM compatibility. At the end of October, StarkWare announced the launch of a zkEVM based on Cairo (named "Kakarot"), but actual development is still in the early stages and has not yet been realized.

Additionally, the Ethereum development team Nethermind is building a "compiler" for Solidity to Cairo, allowing projects written in Solidity to "one-click" translate their codebase into Cairo. It is reported that this "compiler" is still under development, and once operational, it will enable StarkNet to achieve a level of EVM compatibility similar to zkSync 2.0. Nethermind has been dedicated to code translation work and previously launched the Uniswap Warp version on the StarkNet network.

2. Progress:

As one of the earliest developers in the zk-Rollup space, StarkNet's Alpha version was launched on the mainnet in November 2021.

StarkWare launched an upgraded version of Cairo, Cairo 1.0, at the end of September, which is expected to be officially released by the end of 2022. The new version improves the network's DoS attack protection capabilities and reduces gas fees, supports StarkNet's permissionless network requirements, and will simplify and secure the protocol. At that time, the team will also restart StarkNet on the Ethereum mainnet, named "Regensis."

Currently, StarkNet is launching its second testnet on Goerli and has initiated a naming proposal in the community. The new testnet is primarily aimed at developers for testing applications and is not in the public testing phase.

Furthermore, StarkWare announced its token economics in July, with the native token originally scheduled for release in September, but the team postponed the issuance due to technical reasons. The initial issuance of StarkNet tokens is set at 10 billion, with 17% allocated to StarkWare investors, 32.9% to core contributors, and 51% to the foundation (of which 12% is used to fund research and work for the development, testing, deployment, and maintenance of the StarkNet protocol). However, the official statement indicates that no free tokens will be provided to users in the initial phase, and all tokens will be locked immediately upon release.

3. Ecosystem:

The StarkNet ecosystem mainly focuses on DeFi, GameFi, and NFTs, with over a hundred projects deployed on StarkNet. However, some projects are still in the planning deployment stage, and the number of projects that can actually interact is not very high. According to L2beat, StarkNet currently has a total locked value of $3.1 million, an average daily TPS of 0.15, and approximately 279,000 transactions over the past 30 days.

Wallets: Argent X, Braavos (recently completed a $10 million financing led by Pantera Capital)

Cross-chain bridges: Orbiter Finance, the official Ethereum-Starknet cross-chain bridge StarkGate

DeFi:

• 10KSwap: A StarkNet native AMM DEX protocol, now live on the mainnet, currently only trading ETH, USDC, DAI, WBTC, and USDT.
• Alpha Road Finance: A StarkNet native DEX and liquidity staking protocol, currently in the testing phase.
• Brine Finance: An order book trading DEX, still on the testnet.
• Fibrous Finance: An AMM aggregator on StarkNet, still operating on the testnet.
• mySwap: The first AMM DEX on StarkNet.
• zkLend: A lending protocol on StarkNet, featuring two products: Artemis (for DeFi users) and Apollo (for institutions and SMEs).
• GameFi: Loot Realms, GoL2, The Ninth are now live on the mainnet.

1. zkSync

1. Introduction:

zkSync was founded by Matter Labs in December 2019, later than StarkWare, using zk-Rollup technology based on SNARK proofs and supporting zkEVM at the IR level.

Matter Labs released the zkSync v1.0 version in June 2020, which has been online for a long time, and the zkSync 2.0 testnet went live this February. Compared to its predecessor, zkSync 2.0 has significantly enhanced functionality. In zkSync 1.0, users could only experience basic functions such as transfers and NFT minting, while zkSync 2.0 supports EVM compatibility and will open up the deployment of ecosystem applications, making it a truly complete zk-Rollup product.

2. Progress:

On October 28, zkSync 2.0 was officially launched and is currently in the Baby Alpha phase, during which zkSync 2.0 will launch on the mainnet without external projects, mainly for stress testing and various security tasks. Developers cannot access the mainnet but can continue developing on the testnet. The Baby Alpha phase is expected to last about a month.

According to the official roadmap, the fourth quarter (after Baby Alpha) will enter the Fair Launch Alpha phase, where the team will open project deployment permissions to developers. The team plans to achieve a full Alpha launch by the end of this year, but this phase may be extended to 2023 for security reasons. After a series of comprehensive tests, security audits, competitions, and bug bounties, zkSync 2.0 will be open to all users, which is also the closest time to token issuance. Currently, over 150 projects have committed to launching on zkSync 2.0.

Regarding token issuance, Matter Labs' Chief Product Officer Steve Newcomb mentioned in a Twitter Spaces discussion that zkSync will announce detailed information about its token economic model in the first week of November. On November 3, zkSync co-founder Alex G hinted, "Some major news is coming soon."

Related Reading: "Countdown to the Launch of zkSync 2.0 Mainnet: What We Should Know"

3. Ecosystem

According to zkSync ecosystem official website, over 100 projects have been deployed on the network. Additionally, according to L2beat, the total locked value is $6.27 million, with an average daily TPS of 0.37 and a 30-day transaction count of 1.38 million.

Wallets: Argent X, zkSync Portal 2.0 (in zkSync 2.0, users can directly add the zkSync 2.0 RPC node in MetaMask without downloading another wallet)

Cross-chain bridges:

• Orbiter Finance (currently only supports zkSync 1.0, not yet supporting zkSync 2.0 testnet)
• Official cross-chain bridge address for zkSync 2.0 testnet: https://portal.zksync.io/bridge (also supports wallet transfers and receiving test tokens among other functions)

DeFi:

• SyncSwap: A DEX based on zkSync, now live on the zkSync 2.0 network.
• Increment: A decentralized algorithmic perpetual contract protocol based on zkSync 2.0, recently launched on the zkSync 2.0 testnet. However, it is currently only open to users who previously applied for whitelist testing, and the application deadline has passed.
• SpaceFi: A cross-chain web3 platform on Evmos and zkSync, currently running on the zkSync 2.0 testnet.
• Zigzag: An order book DEX supported by zk Rollup, currently only supporting the zkSync 1.0 network.
• Sprintcheckout: A crypto payment platform, currently running on the zkSync 2.0 testnet.

NFT:

MintSquare is an NFT marketplace on Ethereum L2 ZK Rollups (StarkNet and zkSync), currently operating on StarkNet, StarkNet testnet, and zkSync 2.0 testnet.

Additionally, protocols such as Aave V3, Uniswap V3, and 1KX Protocol Beta have planned deployments on the zkSync 2.0 testnet.

3. Polygon Hermez (Polygon zkEVM)

1. Introduction:

In July 2021, the Hermez team announced the development of a fully Ethereum-compatible zkEVM (Hermez 2.0), after which Polygon announced the acquisition of Hermez for $250 million. Polygon zkEVM uses zk-Rollup technology based on SNARK proofs.

Polygon zkEVM has opcode-level compatibility. In the article "Vitalik: The Future of Different Types of ZK-EVM," Vitalik ranked Polygon zkEVM alongside Scroll as a level three solution, placing it among the leaders in EVM compatibility within current ZK Rollups.

In recent promotions, Polygon has emphasized that its zkEVM is "the only decentralized zk-rollup," as it was the first to achieve open-source zk Prover, including a complete and usable source code ZK proof system, and promises a fully open-source, community-driven, permissionless coordinators network with a decentralized auction model featuring verification reward tokens.

2. Progress:

Polygon zkEVM launched a permissionless public testnet on October 10, with Aave, Uniswap, the Web3 social platform Lens, and game studio Midnight Society being among the first protocols to deploy on the zkEVM testnet. Currently, the testnet is primarily open to developers. Polygon zkEVM plans to go live on the mainnet in the first half of 2023.

Additionally, Polygon zkEVM has explicitly stated that there are currently no plans for token issuance; ETH will be used to pay gas fees, while MATIC will be used for staking and governance of Polygon zkEVM.

4. Scroll

1. Introduction:

Scroll was founded in 2021 and completed a $30 million Series A financing at the end of last year. Similar to Polygon zkEVM, Scroll is also dedicated to creating an EVM-equivalent zk-Rollup and claims to be the most compatible zk-Rollup with EVM, allowing Ethereum applications to migrate almost seamlessly to the second-layer network. Bytecode-level compatibility enables compatibility with all languages on Ethereum and tools, significantly reducing the development difficulty on the second-layer network.

Notably, due to co-founder Ye Zhang's extensive experience in ZKP hardware acceleration, Scroll plans to leverage hardware acceleration in ZKP to further improve verification efficiency, establishing a decentralized verification network that distributes ZKP proofs to participants for computation and aggregates the results to form the final proof. This decentralized verification network will be open to everyone and will set up incentive and penalty mechanisms.

Related Reading: "Interview with Scroll Founder Ye Zhang: Where Does Scroll Stand in the zk-Rollup Breakthrough Battle?"

2. Progress:

On October 11, Scroll released an upgraded version of the Pre-Alpha testnet, with some pre-deployed applications like Uniswap v2 allowing users to perform functions such as transfers between L1 and L2. However, at this stage, users need to register to apply for whitelist access to participate in testing. Due to a large number of bot activities, the official team has temporarily slowed down the review of test applications, leading to many users reporting in the community that they have not received email responses. The community suggests changing wallet addresses and emails to reapply.

Scroll has encountered significant cross-chain delays during the testnet period and has also faced issues accessing the faucet for testnet tokens, with the official response attributing this to severe congestion on Ethereum.

Related Reading: "Experience the Ethereum Layer 2 Network Scroll Pre-Alpha Testnet Early"

Additionally, the official team stated that a permissionless testnet will be launched in a few weeks, allowing anyone to interact on the testnet, and developers can deploy contracts on the network without permission. A complete testnet is expected to be launched by the end of this year.

In terms of ecosystem, Web3 social protocol Lens Protocol and oracle RedStone have recently deployed on Scroll's pre-alpha testnet.

Summary:

Overall, while StarkWare and zkSync claim to ultimately achieve zkEVM, they are not bytecode-level compatible, requiring developers to translate and migrate code. In contrast, Polygon zkEVM and Scroll are closer to the Ethereum ecosystem.

However, EVM compatibility is not the only standard for judging the quality of L2 scaling solutions; it serves merely as an objective indicator. In fact, while a fully equivalent EVM is secure, it may sacrifice efficiency. Starkware's Cairo-based virtual machine and Zksync's virtual machine may be more flexible in building zk solutions.

Therefore, there is no essential superiority or inferiority among these protocols, and they are all still in the early stages of development. Beyond ensuring security, the developer experience and user experience will be increasingly important in the future.