L2 Stack Selection Update

Cheers to 2024, Celo Community!

I wanted to share an interim update from cLabs on Celo’s migration to an L2 on Ethereum – the project we’re affectionately calling CEL2.

You’ll recall that in December we introduced a comprehensive framework designed to guide the selection of an L2 Stack, as the next step in the project’s technical roadmap. I wanted to give you an update on this process. We try to work in the open as much as possible, and this update aims to provide context on where we are.

After getting some great community feedback on the framework, and revising it based on that, cLabs set to work evaluating the options. Despite limiting ourselves to four candidate stacks, this has proven a real challenge – because we are considering a ton of different dimensions, both technical and non-technical, and frankly, because each of the candidate projects are awesome achievements with strong roadmaps backed by strong teams and communities, and are each moving fast. We’re trying to find the best stack for Celo’s needs, not the best stack, so we’ve also been thinking hard about where we see Celo going, too.

As the year drew to a close, the engineering teams at cLabs delved into the intricate task of technically evaluating the L2 stacks. We notched up dozens of meetings and reviews, continuous collaboration, and wrote, debugged and deployed code. The process has been more than a checklist; it has been a dynamic exploration of possibilities, lessons, insights, and deep technical discussions. While we’re still completing this process, it’s safe to say that we’ve learnt a lot and come away with a deep appreciation for the builders on these projects.

Here are some stack-specific updates, in the order that they made their proposals on the forum:


We have continued our dialog with the Optimism team, and have a great ongoing collaboration. This has also led to an L2 Unplugged session with Ben and Marek (and we’re excited to schedule follow-up episodes with the other stacks).

The cLabs team has an internal OP Stack based testnet live, which has helped the team become very familiar with the codebase. It has also helped us progress work on separating the Celo protocol into a patch queue, an activity that is necessary whichever stack is chosen.

A lot of our work in the last couple of weeks has been focused on understanding Superchain governance, and the path towards protocol alignment that that would entail, through contributing or collaborating on APIs and implementations for features such as shared sequencing, off-chain DA and Celo-specific precompiles.


We’ve been working closely with the Polygon team exploring potential avenues for integrating Celo into their Interop layer using a Polygon CDK prover. We’ve benefited hugely from Brendan and William’s deep technical expertise, and appreciate the Polygon team’s work to provision two testnets for us.

Two primary approaches are under consideration: Launching a CDK chain with a Type 2 prover from the Hermez stack, or integrating their Type 1 stateless prover with our current stack.

We’ve been impressed by the Hermez stack: it’s a more mature codebase, and is cost-effective. We’re working on evaluating the migration effort that it would entail for bridges and other projects that make assumptions about storage layout.

Polygon’s newer Type 1 stateless prover is an intriguing option. It would provide greater compatibility and a far simpler migration path, including the ability to migrate and implement Celo-specific precompiles. Moreover, the LXLY bridge can accommodate chain-specific changes of the zkEVM. We’re working to understand licensing and roadmap timing for this.


The zkSync team have been a pleasure to collaborate with – they demonstrated remarkable proactivity, organizing meetings, sharing their 2024 roadmap, and engaging in detailed technical discussions with our engineers. The team provided a Type2 EVM-equivalent testnet for our tests and were highly responsive to bug reports. Alex Gluchowski, the co-founder of Matter Labs, joined our community call and wrote an insightful post, providing his take on the exercise of applying the suggested framework to the zkSync Stack & zkSync.

Promising features that align well with Celo’s requirements include low block times of approximately 1 second, ensuring swift finality for transactions. The native account abstraction support provides an opportunity to implement gas fee currencies efficiently. We like having the flexibility for general changes to the zkEVM, along with the ability to migrate and implement Celo-specific precompiles. Additionally, the platform boasts lower withdrawal-to-L1 times compared to Optimistic solutions, contributing to an efficient user experience. While the shared bridge presents collaboration opportunities, we are working to understand how that would be able to accommodate Celo-specific zkEVM changes.


The team had fun kicking the tires on a local deployment of the Arbitrum codebase. It was clear to the cLabs team that the codebase is mature and would provide a production-proven foundation for Celo. The migration path would be straightforward compared to ZK-based solutions. Ongoing developments in the next generation of fault proofs underscore the platform’s commitment to future resilience.

Just a few days ago, the Arbitrum Foundation publicly announced the Arbitrum Expansion Program, setting out licensing terms and fee revenue split for building L2s based on the Orbit code base. We’re working with the Foundation and Offchain Labs team to get a complete picture of the economic implications of adopting the Arbitrum stack.

While we were able to gather a lot of info from public sources, documentation, and running the stack locally, we also had the opportunity to pose questions to the Arbitrum team in our shared chats and calls. We are thankful for this insightful opportunity!

Next steps

As this post hopefully conveys, a lot of work has been done, but there’s more to do.

As we wrap up the technical evaluations, we’re moving to evaluating the non-technical dimensions described in the framework. This is different to evaluating published software. It’s harder to predict exactly how quickly we’ll be able to conclude this, especially as the candidate stacks are actively assembling their economic terms and incentive programs.

We’re working as fast as we can to get a comprehensive proposal that we feel confident proposing as the best route forward for Celo. In the mean time, there’s a lot of roadmap engineering work we’re able to progress. As always, we’ll post regular updates here, and we welcome questions and suggestions from the community.

cLabs Team


Interesting updates. Looking forward to the progress. I’m interested to learn more about superchain upon OP stack


Hi @tim and team!

Thanks for providing a detailed update on the L2 Stack selection. Having worked closely with dozens of Celo stakeholders over the past months, I can attest that almost everyone is following the developments closely and building up their knowledge around L2s.

There are also groups forming with specific preferences regarding which Stack Celo should select. I’m curious about the right moment for the broader Celo ecosystem to start chiming in with their preferences and suggestions. I think most people are waiting for cLabs to wrap up their technical review.

Do you imagine releasing an next update with an initial conclusion of the Technical evaluation?


The decision must strenghteing DTV on CEL2


Great overview.

Not sure if you are interested in others chiming in with the preferences, but having previously built PGN (part of the OP Superchain), I’m heavily biased towards choosing Optimism.

A few reasons:

  1. Superchain interoperability. OP Labs is building a ton of new tools making interoperability easier for developers and end-users
  2. I’m bullish on Base. Joining the superchain means their success = your success. Specifically, easier on-ramps and shared liquidity with superchain bridging.
  3. Values alignment. Optimsim is a big supporter of public goods leading one of the largest RetroPGF rounds to date. With Celos PG funding strategy in 2024, I believe there’s a lot we can gain from being part of this ecosystem.

Happy to expand in more detail :slight_smile:


Could you update the OP post to include a poll where we can informally vote on what stack we think should be chosen?

An important lesson from PGN was their inability to build out features like contract secured revenue, due to requirements of maintaining parity with bedrock

Are the other options more customizable? Flexibility is an important criteria that too often gets left out until after we’re locked in to a stack


Also looking at Polygons underhanded tactics for getting ApeDAO to build on their CDK, i’d advise staying as far away from them as possible

Consider the facts ;

  1. Polygon loses the snapshot temperature check for their kit to be used by ApeChain


  1. Sandeep removes the votes of Machi Big Brother and Horizen Labs votes because he believes they were self-interested

  1. Incredibly, his CEO Marc Boiron then goes on to buy APE tokens and vote for themselves !

People who pursue their self-interest under the garb of morality are the worst sort to deal with. Stay the hell away from Polygon

Edit : there is much we can learn from ApeDAOs ongoing process to select a L2 stack, details here



I have been thinking about Celo and the broader web3 ecosystem’s interest in what does it mean to be “the best stack for Celo’s needs” (though I also didn’t see Celo being compared to a character in an ancient Greek poem on my 2024 bingo card!).

From the initial cLabs proposal onwards, the key goal has always been to analyze the best possible technical stack choices that maximize Celo’s long term ability to be the infrastructure for all projects building and solving real world problems. The Celo Foundation is supporting this important work and partnering with cLabs, especially around the components of the evaluation framework shared earlier that touch on ecosystem and governance. I figured it was worth sharing some of our thoughts here ahead of cLabs gearing up to make its recommendation to the community.

Bankless recently had a great episode (The Ethereum L2 Token Thesis) - I highly recommend giving it a listen and think it succinctly gets to a few key points:

  • In the longer run, most L2s should have near-zero fees like Celo today
  • In that world, L2s that have the most sustainable transactions win
  • L2 value is the difference in the fees earned and the fees paid to the different components of the stack to make it sustainable and user friendly

Considering this perspective, it is critical (ahead of cLabs’ recommendation) to understand the cost (today and in the future) across the different components of the L2 stack, including sequencer fee share arrangements.

Celo is in a strong position given the above framework and at Celo Foundation our focus will remained unchanged: helping builders in our ecosystem launch and grow great applications that drive real world value.

Additionally, since the initial proposal, it has become clearer that - especially in the short- to medium-term - each of the ‘stacks’ looks to create a sort of alliance among participating chains (eg Superchain, Hyperchain). While that has advantages around low cost messaging/bridging, sharing liquidity and sharing the cost of ‘Ethereum security’, it may also come with constraints around the independence of Celo with respect to upgradability and scenarios for exiting such an alliance. In the long term, I would expect these alliances to be subsumed by just one big Ethereum L2 alliance, with shared sequencing and shared block builders providing low cost messaging/bridging across L2s of different stacks.

With that in mind, a few items from the initial evaluation framework stand out to me in particular as being important to consider:

  1. Positive-sum platform growth opportunities: What are the other members of each alliance, today and tomorrow? What are ways to bring value to each other?

  2. Roadmap influence: What influence does Celo have both informally and via on-chain voting to shape the roadmap and future of a given alliance? Are there roadmap decisions that could be adversarial for Celo? On the other hand, if cLabs and Celo ecosystem developers end up becoming key contributors to the roadmap, clear contribution incentives (e.g., grants, retroactive funding) need to be determined. Necessary governance voting power can come through either grant arrangements or token swaps.

  3. Independence within Ethereum: As outlined before, it is important that the Celo community can fix, modify, and extend the codebase that comprises Celo, and that the platform can be maintained and governed in a decentralized manner with minimal constraints. It is our preference to use permissive open-source codebases and to avoid complex licensing arrangements. At the same time, it is also important to the community to continue to evolve and improve Celo governance, as is the case currently with the Public Goods Funding Strategy.

Hope this helps shed some additional light regarding how we at Celo Foundation consider thinking about the economic implications behind the stack selection decision.

The best analogy I can come up with is how one picks a university as a student - say you are great at sports and you are being offered scholarships of various amounts; while that’s one factor in your decision, other important variables such as the curriculum, reputation, location, cost of living, where your friends are going, etc. will all play a role in your ultimate decision coming down to what career you may want to pursue long term and finding success and happiness as a human being in the long run.

Fwiw, I don’t think there are many (any?) precedents for this kind of ‘strategic partnership’ between DAOs/communities, so, as always, any feedback is welcome as progress moves forward on this exciting next step.


Hey Rene, thank you so much for sharing your insightful thoughts. And the timing is perfect to start talking economics now given the technical selection is well underway. When I challenge the cLabs team to include economics in its roadmap, I already had some thoughts in my mind and have been trying to steer the discussion around this topic here, here. Happy to chat live sometime soon. Maybe in EthDenver is you are coming as well?


Hi @hhe - happy to meet up at ETH Denver and chat irl!

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Sound great! I will be in EthDenver from Mon-Sat (2/26-3/2). I will DM you then.

Can you share any updates? seems like so delayed


Yeah would love an update. Where are we on the roadmap? What deliverables have you guys finished? Let’s get this stack selection proposal out and the ball rolling already. Give your thoughts on the different stacks and let the community vote on it.

It seems the estimated timelines were way off. As everything has been delayed for months. What was the purpose of the 2 million that was issued to Clabs if it’s still being delayed by this much? The whole point of the added funding was to expedite things.

Too many projects/companies in the Celo ecosystem keep taking and asking for money from the community fund but there is no accountability or anyone independently enforcing the things they outline in their proposals.

Celo foundation monitoring the use of funds that was issued to Clabs is like the police investigating the police.


The team has a duty to transparently disclose progress to the community. Significant delays have occurred since the milestones were initially announced in the roadmap. I propose that the team update the schedule and regularly share progress with the community - for example, on a weekly or bi-weekly basis. Sharing weekly progress of the project is common in the blockchain industry.


Gm! We’ve had a bunch of folks from Celo Foundation & cLabs at ETHDenver share updates there on various panels and talks with the broader community (https://x.com/Celo/status/1760424199200592291), while spending additional face-to-face time with potential stack partners and Celo ecosystem projects.

As per previous posts, in this current part of the process, we are considering additional partnership implications with respect to each stakeholder and the Celo community, and preparing a final timeline for sharing this without delay.

In the meantime, please join this week’s L2 Unplugged with the zkSync team for more re: their technical innovations (https://twitter.com/zksync/status/1766852932375380000)

Rest assured, everyone is working towards finalising the stack selection, and there’s a bunch of stack-choice independent L2 work that continues to happen in the meantime. Ofc other ecosystem work isn’t stopping either, including foundational integrations e.g., native USDC and as of yesterday, USDT (forthcoming; Tether Token (USDT) to Launch on Celo)


Hi Rene, could you please do the community a huge favor and provide us an update on the selection process for the L2 stack?


Any update would indeed be nice.

The cLabs funding received for CEL2 (untouched as of today) is 3x the USD budget initially asked for yet we are lagging by 5 months on the first milestone itself.

At the very least we should start discussions and choose the stack ASAP.


Can we have an update?

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FYI Quick Update on L2 Stack Selection