Layer 2 Rollups Projects in 2021: A Comparison by@josephkk

Layer 2 Rollups Projects in 2021: A Comparison

July 27th 2021 13,420 reads
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Crypto Enthusiast, Trader & Investor

Ethereum layer 2 is a collection of solutions that are specifically designed to scale applications by handling transactions off the Ethereum Mainnet, Layer 1. Transaction speed on the network is affected when the network is busy, resulting in a poor user experience for many DApps. The gas prices increase, making Ethereum very expensive for its users. In comparison, Ethereum L2 runs on top of Ethereum L1. Operating on Layer 2 frees Layer 1, taking transactions off the main chain. Due to transactions being processed off-chain on Layer 2, it results in higher transaction speed, faster confirmation time, and lower gas.    Layer 2 has numerous solutions, each with its own specification, such as Optimistic Rollups, ZK-Rollups, plasma, etc.

In this article, we will compare Ethereum Layer 2 Rollups projects.

What are Rollups? Rollups are solutions that execute transactions outside the Ethereum Layer 1. The transaction data or proof of transaction is on Layer 1, therefore, ensure security. It reduces the fee for users, allows open participation.

There are two types of Rollups out there.

Zero-Knowledge Rollups Also known as ZK-Rollups, it runs computation off-chain and submits validity proof to the chain. ZK-Rollups do not require transaction data. Therefore, validation of block is quicker and cheaper.

Optimistic Rollups Optimistic Rollups assume that transactions are valid by default and runs computation only in the case of a challenge by utilizing fraud-proof. In this case, computation is slow.

Rollups Projects Comparison

The following are ZK-Rollup implementation projects.



zkTube uses Layer 2 ZK-Rollups to provide low transaction fees and high throughput transactions.  It ensures security by tracking the history of state roots and the hash of each batch.

It is solving Ethereum scaling while ensuring transaction speed and security.

It reduces transaction fees through batch processing and ZK proof functions.

It is the first application utilizing PLONK technology for mining and is eco-friendly to decentralized energy management.

It is an outstanding project both in terms of performance and security.

zkTube is using Zero-Knowledge Rollups instead of Optimistic Rollups considering the speed of withdrawals that in case of Optimistic Rollups take one week. The speed can be increased but it reduces efficiency by increasing cost ultimately. Whereas ZK-Rollups make zkTube fast, secure, and cost-effective.

It allows users to store their assets in a ZK-Rollup with Layer 1 security. Meanwhile, enabling users to interact with Layer 2 contracts. Therefore, offering effective interaction between Layer 1 and Layer 2.

It allows multiple transactions to be bundled and executed as a single transaction on a layer at once.

zkTube has developed the ZK proof algorithm into a miner, composing an architecture of Provers grids and miner verification nodes.

zkTube is working to improve the current Ethereum system by breaking through the existing performance limitations to host a larger ecosystem.

zkTube offers PayTube Wallet that enables users to access any Ethereum decentralized apps with just a one-click link.



Loopring is an Ethereum Layer 2 scaling protocol that allows the building of high-throughput, low-cost, non-custodial AMMs and payment applications on Ethereum by leveraging ZK proofs.

It is highly secure, providing 100% Ethereum-level security. Users in the Loopring ecosystem have full control of their assets ensured by ZK-Rollups.

Loopring powers payments by batch-processing off-chain requests via ZK-Rollups.  Most operations, such as trade and transfer settlements, etc., off the Ethereum blockchain, reduce gas consumption and overall transaction costs.  Loopring can settle up to 2025 trades per second.

StarkWare (ZK-STARK)

ZK-STARK is a cryptographic proof technology that allows users to share data and perform computation with third-party without revealing data.

It improves scalability by allowing developers to move computation and storage off-chain.

ZK-STARKs are scalable in computational speed but are vulnerable to attacks from quantum computers due to cryptography.

It satisfies asymptotically optimal efficiency.

DeversiFi has integrated ZK-STARK that allows 9000+ trades per second.


zkSync solves Ethereum scalability by ensuring 100% security.

zkSync supports meta-transactions, instant confirmation with affordable finality, and less expensive privacy.

zkSync is unconditionally permissionless and growing down the path of progressive decentralization.

It takes 10 minutes for finality and has the lowest real tx costs-0.5k gas per tx.

Users can sign the transaction with their usual Ethereum wallet by signing an EIP712 message.


Aztec provides ZK-SNARK service to the mainnet enabling the scaling and shielding of transactions.

Aztec is the ultimate security shield from the internet of money, ensuring user’s data protection on Web 3.0. The sender and recipient identities are hidden. They are also ensuring balance and code privacy.  Private transactions are computed in seconds. Each Rollup aggregates 112 transactions, making users pay a much lower gas fee by splitting the cost of a single proof.  Aztec can scale on-demand up 300 transactions per second.

Hermez Network

Hermez is an open-source ZK-Rollup solution that enables secure, economical, and usable token transfers on the wings of Ethereum.

It offers computational integrity for secure transactions.

Using ZK-Rollups, Hermez offers 90% transfer cost reductions, allowing more accessible financial services for mainstream adoption.

It guarantees computational integrity and on-chain data availability.

Anyone can bid in a decentralized auction to create the next batch on Hermez, and each successful transaction is rewarded with collected transaction fees.

Optimistic Rollups

The following are Optimistic Rollup projects.


Optimism is a scalability stack for Ethereum that offers instant transactions and scalable smart contracts. It is built to behave and feel like Ethereum but cheaper and faster.

Transactions are checked via a Verifier to be incorrect or correct. When it successfully proves a transaction result incorrect, Verifier is rewarded.

OVM Account contracts are redeployed able contracts Layer 2 contracts, representing a user and providing a form of “account abstraction.”

Transaction fees on Optimistic Ethereum. Cost is related to primary actions taken by users while interacting with the platform.

You can easily add or connect Optimistic Ethereum via MetaMask both manually and using

Off-chain Labs Arbitrum Rollups

Off-chain Labs is the ideal scaling solution for DeFi apps and any Ethereum contract.

It offers a secure and economically efficient blockchain experience without any limits.

Transactions on Arbitrum use 2-3k Ethereum gas. It can be further can down using the BLS signature.

It is EVM compatible on the bytecode level. There is no need to use any custom compiler.

It breaks out the limitations of Ethereum contract size and transaction gas limit.

Fuel Network

Fuel Network empowers fast, secure, and cost-efficient ERC-20 token transfers and swaps.

It is completely decentralized, non-custodial, censorship-resistant, and permissionless.

It has up to 10,000 TPS surge intake capacity.

It allows users to pay fees in any token and complete withdrawals within 10 minutes using atomic swaps.

No burdensome proof generation with high latency and no exotic cryptography.


Cartesi is a Layer 2 platform composed of both blockchain and off-chain components.

It allows large-scale verifiable computations to run that are easily integrated into smart contracts.  DApps running inside Cartesi can process a virtually unlimited amount of data.

It allows DApps to benefit from vastly increased computing capabilities Off-chain while ensuring security.

It is built with the goal of shielding users from as much complexity as possible.


OMGX is a Layer 2 solution maintained by OMG and Enya teams.

It runs in EVM- compatible virtual machine, which allows it to handle any smart contract running on Ethereum.

OMGX enables developers to leverage much richer compute capabilities to create more compelling DApps.

It is the next generation optimistic rollup that offers economical smart contract support and stake rewarding.

OMGX onboard team assists developers to ensure smooth transactions for porting contracts to Optimistic Rollups.


Layer 2 solutions seem very viable and allow developers to start projects by deploying them. Vitalik Buterin thinks that Optimistic rollups are suitable for near terms while ZK-Rollups are used for longer. Layer 2 solutions are needed because otherwise, it would be unnecessarily expensive to use blockchain applications.

Vitalik says, “ If you are building applications, you must also be facing problems in scalability. Every transaction consumes gas, and the price of Ether (ETH) has been high. Therefore, if you are looking for ways to optimize your applications, a Rollup scaling solution is highly recommended.”

Since these solutions are new and slowly being deployed, we can expect more out of these in the future.

Stay tuned!

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