Breaking News
Investing Pro 0
🙌 It's Here: the Only Stock Screener You'll Ever Need Get Started

Optimistic Vs. ZK Rollups: A Deep Dive into Ethereum’s Layer-2 Scaling Solutions

By Ulrik LykkeCryptocurrencyMar 21, 2023 06:51AM ET
Optimistic Vs. ZK Rollups: A Deep Dive into Ethereum’s Layer-2 Scaling Solutions
By Ulrik Lykke   |  Mar 21, 2023 06:51AM ET
Saved. See Saved Items.
This article has already been saved in your Saved Items
Add to/Remove from Watchlist
Add to Watchlist
Add Position

Position added successfully to:

Please name your holdings portfolio
Add to/Remove from Watchlist
Add to Watchlist
Add Position

Position added successfully to:

Please name your holdings portfolio

The Ethereum blockchain is undoubtedly a game-changer in the decentralized economy. However, despite being around since 2015, it is still plagued by several challenges, such as scalability, speed limitations, and high network costs. Fortunately, the rise of layer 2 scaling networks, such as Optimistic and Zero-knowledge Rollups, has brought a solution to these problems.

Rollups offer a faster and cheaper alternative to traditional blockchain transactions by processing them on a separate, faster blockchain (known as a Layer-2) and then returning the transaction data to the parent blockchain (the Layer-1 or mainnet) at a fraction of the cost.

In essence, Layer-2 scaling solutions allow users to enjoy the best of both worlds: The speed and affordability of Rollups combined with the security of the underlying Layer-1 blockchain.

In this article, we will explore the two main types of Rollups, optimistic and zk-rollups, and delve deeper into how these two scaling solutions differ in terms of network consensus and other fundamental factors.

Optimistic vs ZK Rollups

Optimistic rollups are a layer 2 protocol designed to increase the throughput of Ethereum’s base layer. They achieve this by processing transactions off-chain, which significantly improves processing speed while decreasing the computation on the primary Ethereum chain. Optimistic rollups differ from other scaling solutions, such as sidechains, in that they derive their security from the mainnet.

They are called “optimistic” because they assume that off-chain transactions are valid and do not publish proofs of validity for transaction batches posted on-chain. Instead, they use a fraud-proving scheme to detect incorrect computations in transactions. When a rollup batch is submitted on Ethereum, there is a challenge period during which anyone can challenge the results of the transaction by computing a fraud-proof.

Similarly, Zero-knowledge rollups bundle transactions into batches that are executed off-chain. ZK-rollup operators submit a summary of the changes representing all the transactions in a batch, rather than transmitting each transaction individually. However, unlike optimistic rollups, ZK-rollups produce validity proofs to demonstrate the accuracy of their changes. The validity proof offers cryptographic assurance that the proposed changes to Ethereum’s blockchain are the result of executing all the transactions in the batch.

That said, it is pretty obvious that these Layer-2 solutions differ to an extent. Here is a brief breakdown on how they compare in the most fundamental factors that determine the efficiency and effectiveness of any Layer-2 scaling solution.

  1. Transaction Finality and Costs

Transaction finality is one of the most important factors to consider in this comparison. Zero-knowledge rollups enable immediate withdrawal of funds, while optimistic rollups feature a one-week delay in the challenge period. Users must wait through the challenge period before withdrawing funds, causing a delay in transaction finality.

However, it is worth noting that Optimistic rollups have lower costs because they don’t require proof for transactions unless challenged. Meanwhile, Zero-knowledge rollups have higher network costs due to the computational proof required for each transaction block and the need for high-end hardware.

  1. DeFi Compatibility

Optimistic rollups, such as Optimism and Arbitrum, offer greater compatibility with DeFi applications due to their EVM compatibility. The Ethereum Virtual Machine (EVM) is a virtual CPU used by Ethereum to execute smart contract code. EVM compatibility allows for the creation of an EVM-like code execution environment, making it easy for developers to migrate smart contracts to an EVM-compatible chain without having to write the code from scratch.

In contrast, Zero-knowledge rollups face more limitations in terms of DeFi compatibility. However, the emergence of ZK-EVM projects, such as ZKSync, Polygon, and Scroll, is showing promising results in general-purpose support for DeFi smart contracts.

  1. Network Security

When comparing optimistic rollups to zk-rollups, one of the most crucial factors to consider is security. Optimistic rollups rely on incentives and rewards to encourage users to ensure the security of the rollup. Validators receive compensation for submitting successful fraud-proof evidence, which incentivizes them to act honestly.

Conversely, zk-rollups use cryptographic proofs to ensure security. Both types of rollups compete against each other on the basis of security, with each utilizing different methods to provide users with the highest level of protection.

  1. Programming Efficiency

Ease of programming is particularly important for DApp developers, and Optimistic rollups have an advantage here. This is because they offer data compression flexibility and EVM compatibility, making programming easier. In contrast, Zero-knowledge rollups don’t require publishing transaction data on Ethereum, but they require clear cryptographic proof, making programming more difficult.

Optimistic roll ups are easier to use, less costly, and have lower programming complexity, but they have a delay in transaction finality and rely on users to ensure correctness. Zero-knowledge rollups guarantee authenticity, have immediate withdrawals, but have higher costs and require clear cryptographic proof.

Possible Drawbacks

Despite leveraging Ethereum’s core security guarantees, rollups still present certain risks compared to Ethereum’s mainnet.

One major concern is the potential for bugs in roll-up smart contracts, which are not uncommon in any program built on Ethereum. While audits and fail-safes can help prevent attacks, relying on an external program to handle transactions entails some risk.

Moreover, both types of rollups are relatively new and operate on networks that are often centralized. In some cases, the rollup’s development team retains partial control over the network and can potentially pause or shut it down.

Many rollups still depend on centralized “sequencers” to efficiently coordinate transactions on the layer 2 chain. While a sequencer cannot falsify or modify transactions, it could censor or re-order them to gain some advantage.

On the brighter side, these upcoming rollups intend to decentralize in some form. For example, Optimism has begun the transition to community governance, and improvements to rollup technology should address some of the concerns around centralized network control.

Latest Highlights in the Rollups Ecosystem

The Layer-2 ecosystem has grown rapidly in recent months due to its value proposition in DeFi innovations. A lot of activity is happening in infrastructure development and network integrations, particularly in optimistic rollups such as Optimism and Arbitrum.

Optimism will release Bedrock in April, a major update promising modularity, simplicity, and Ethereum equivalence for L2 solutions. This update is expected to bring significant performance improvements, such as lower transaction costs, higher throughput, and faster sync speeds.

Additionally, Coinbase’s (NASDAQ:COIN) recently launched L2 solution, Base, will use Optimism’s technology, and Coinbase is joining Optimism as a core dev to build the open-source OP Stack that powers Optimism. Both companies share a vision for a network of interoperable layer 2 solutions or rollups that can scale Ethereum together.

On the other hand, Reddit chose Arbitrum Nova for its community points, demonstrating that hubs for specific purposes are already a reality. “We found Arbitrum optimistic rollups to be the most promising scaling technology for Community Points,” stated an earlier Reddit post on scaling the platform’s community points with Arbitrum.

Optimistic Vs. ZK Rollups: A Deep Dive into Ethereum’s Layer-2 Scaling Solutions

Related Articles

Ulrik Lykke
Crypto Markets Not Out of the Woods Yet By Ulrik Lykke - Jun 02, 2023

Global markets continue to face headwinds as developed economies grapple with persistent inflation, remaining above the desired 2% level. Notably, Germany, the economic powerhouse...

Naeem Aslam
What's Going On With Bitcoin? By Naeem Aslam - Jun 01, 2023

Today there is a lot of focus on the US data, especially the US ADP number, which is expected to print a solid reading, which would mean that the US dollar index may pick up more...

Optimistic Vs. ZK Rollups: A Deep Dive into Ethereum’s Layer-2 Scaling Solutions

Add a Comment

Comment Guidelines

We encourage you to use comments to engage with other users, share your perspective and ask questions of authors and each other. However, in order to maintain the high level of discourse we’ve all come to value and expect, please keep the following criteria in mind:  

  •            Enrich the conversation, don’t trash it.

  •           Stay focused and on track. Only post material that’s relevant to the topic being discussed. 

  •           Be respectful. Even negative opinions can be framed positively and diplomatically. Avoid profanity, slander or personal attacks directed at an author or another user. Racism, sexism and other forms of discrimination will not be tolerated.

  • Use standard writing style. Include punctuation and upper and lower cases. Comments that are written in all caps and contain excessive use of symbols will be removed.
  • NOTE: Spam and/or promotional messages and comments containing links will be removed. Phone numbers, email addresses, links to personal or business websites, Skype/Telegram/WhatsApp etc. addresses (including links to groups) will also be removed; self-promotional material or business-related solicitations or PR (ie, contact me for signals/advice etc.), and/or any other comment that contains personal contact specifcs or advertising will be removed as well. In addition, any of the above-mentioned violations may result in suspension of your account.
  • Doxxing. We do not allow any sharing of private or personal contact or other information about any individual or organization. This will result in immediate suspension of the commentor and his or her account.
  • Don’t monopolize the conversation. We appreciate passion and conviction, but we also strongly believe in giving everyone a chance to air their point of view. Therefore, in addition to civil interaction, we expect commenters to offer their opinions succinctly and thoughtfully, but not so repeatedly that others are annoyed or offended. If we receive complaints about individuals who take over a thread or forum, we reserve the right to ban them from the site, without recourse.
  • Only English comments will be allowed.
  • Any comment you publish, together with your profile, will be public on and may be indexed and available through third party search engines, such as Google.

Perpetrators of spam or abuse will be deleted from the site and prohibited from future registration at’s discretion.

Write your thoughts here
Are you sure you want to delete this chart?
Post also to:
Replace the attached chart with a new chart ?
Your ability to comment is currently suspended due to negative user reports. Your status will be reviewed by our moderators.
Please wait a minute before you try to comment again.
Thanks for your comment. Please note that all comments are pending until approved by our moderators. It may therefore take some time before it appears on our website.
Are you sure you want to delete this chart?
Replace the attached chart with a new chart ?
Your ability to comment is currently suspended due to negative user reports. Your status will be reviewed by our moderators.
Please wait a minute before you try to comment again.
Add Chart to Comment
Confirm Block

Are you sure you want to block %USER_NAME%?

By doing so, you and %USER_NAME% will not be able to see any of each other's's posts.

%USER_NAME% was successfully added to your Block List

Since you’ve just unblocked this person, you must wait 48 hours before renewing the block.

Report this comment

I feel that this comment is:

Comment flagged

Thank You!

Your report has been sent to our moderators for review
Continue with Google
Sign up with Email