# Panel | Rollup architecture and comparative analysis of sequencer approaches | ETHDam III - 2025 - Channel: [CryptoCanal](https://streameth.org/cryptocanal) - Date: 2025-10-07 - Duration: 33:45 - Watch: https://streameth.org/watch/yt-i3FlSzRHX3M - YouTube: https://www.youtube.com/watch?v=i3FlSzRHX3M ## Description Welcome to the 3rd Edition of ETHDam, hosted May 9–11, 2025 in Amsterdam. This year, we brought together the brightest minds in privacy, security, and AI for a unique 48-hour hackathon + conference combo. 🌷 https://www.ethdam.com// 🌷 ------------------ Rollup architecture and comparative analysis of sequencer approaches | Panel | ETHDam III - 2025 πŸŽ™ Panelists: 1. Ameen Soleimani - 0xbow - Advisor / https://twitter.com/ameensol https://0xbow.io/ 2. Lisa Akselrod - Aztec Labs - DevRel/Tech.writing / https://twitter.com/cryptobuilder_ https://aztec.network/ 3. Omer Talip Akalin - Citrea - DevRel Engineer / https://twitter.com/otaliptus https://citrea.xyz/ 4. Moderated by: Pavel Emdin - Igra Labs - CEO / https://twitter.com/emdin https://igralabs.com/ ------------------ About ETHDam & CryptoCanal ETHDam is powered by CryptoCanal, an education and events platform rooted in Amsterdam, expanding into Rotterdam and ZΓΌrich. Keep up with us to see updates on future events: https://www.cryptocanal.org/ Follow CryptoCanal on X: https://twitter.com/CryptoCanal Join CryptoCanal TG Community: https://t.me/CryptoCanalCommunity Join CryptoCanal Discord: https://discord.com/invite/XJVjpCqQBz CryptoCanal unites crypto enthusiasts committed to making a positive impact. Unapologetically political, we prioritize education, events, and services while championing cypherpunk values like privacy, sovereignty, and censorship resistance. ------------------ πŸŽ₯ Credits: Intro / outro by babyPRO - https://babypro.art/ ETHDam Photography by Paulus – https://concretestate.eu/ ------------------ Special thanks to our partners who made ETHDam possible: 🌹 Hackathon – Bouquet: Oasis Network https://oasisprotocol.org/ 🌷 Hackathon – Petal: Circles https://aboutcircles.com πŸ’› Conference – Gold: Zano https://zano.org/ Dash https://www.dash.org/ Bitvavo https://bitvavo.com/en 🩢 Conference – Silver: Igra Labs https://igralabs.com/hero πŸ’› Conference – Copper: Lido https://lido.fi/ DeTrip https://detrip.travel/ Cake Wallet https://cakewallet.com/ The Grid https://thegrid.id/ Calimero Network https://calimero.network/ 0xbow https://0xbow.io/ Mina https://minaprotocol.com/ JobStash https://jobstash.xyz/ Cyber Capital https://www.cyber.capital/ POAP https://poap.xyz/ Acronym Foundation (Supported our Top 10 Hackers) https://acronymfoundation.org/ 🌱 Sponsor: EF Ecosystem Support Program https://esp.ethereum.foundation ------------------ 0:00 – Intro & Panel Kickoff 2:36 – The Fragmented Rollup Landscape 6:08 – Based Rollups: One vs Many 10:04 – Sequencer Centralization Risks 14:59 – Aztec’s Decentralized Sequencer 18:54 – Unilateral Exits & ZK Rollups 21:12 – Do Users Actually Care About Decentralization? 28:29 – MEV & Bitcoin Rollup Controversies ## Transcript Welcome to EA to E to E to E to E. So, we're going to jump in and this goes from very fun from the AI and we go straight into hardcore tech discussion. Um, so I'd like to introduce uh or ask Pavl to come up uh to the stage and uh you will take it away and um introduce the other panelists. Welcome. Are you excited? We'll grab you a microphone. Take whichever one you want. Is it the first test? Which kind of which color of microphone? Microphone. Whatever you want. Yes. Uh after this, don't forget that the slido is active. So, uh, if you have questions as this panel is ongoing, please make sure to ask it to the slideo. Good luck, guys. Thank you. Uh, yeah, you quit. It's fine. Uh, thanks for joining us. Uh, I promise this would be interesting. Uh, it's not like it's controversial because it's not about privacy. It's about uh uh Ethereum and not only Ethereum uh ecosystem challenges specifically rollups and centralization of sequencers and we have a like a crazy lineup here. I'm really excited to have these guys uh here with us. Uh but yeah, they will introduce themselves. So yeah, give them first like round of applause. They worth it. Yeah. Yeah. And let's let's kick off. I mean let's start from you. Hi, my name is Amin Solommani. I'm the CTO of Oxbow, summoner of Malikdo. Been building Ethereum stuff for a long time. Today, I'm going to learn what a a sequencer is. I hope so. Yeah. And yeah, if it's if it's okay to have them centralized, should we care at all? And should we care about the centralization or maybe we just should build databases instead? Lisa, my name is Lisa Axelrod. I'm part of devil team atte privacy toarium. Hi everyone, my name is Talip. I'm a de engineer at Citra and uh I used to be a protocol but now I mostly talk with both Ethereum people and Bitcoin people which is a fun job and I'm also on stage to learn what a based rollup is maybe. So yeah, this will be fun. I think Aurora uh there is no like 100% clear understanding what's the basic rollup is and like should we even care about this? So uh but I want just to start with like uh from the middle essentially like how you guys see the rollup uh landscape today and the state of uh model architecture of programmable blockchains in the general. What's your thoughts on that? Um it's probably a good idea because like not everybody wants the same thing. Uh I think there's sort of two different schools of thought. One is like we kind of initially wanted sharding on Ethereum and so that was that we're going to have a whole bunch of homogeneous uh you know computation zones that look the same and work the same and that have that can natively interoperate between them and then what we ended up with is like a free-for-all of all sorts of different types of rollups uh and you know L2s built on top of Ethereum for different types of you know applications. run by different groups of people. Uh I think it was kind of inevitable because people actually want their own thing and so you you know Coinbase wants to have base and Kraken wants inc and you know they're both based on optack and then arbitum exists and there's Athena now building some other thing on that uh what was it called? um I forget what it's called, but uh and and so it it's uh once you have that then everybody tries to figure out how to make them work together and then we end up trying to figure out how we get back to the kind of interop that we originally thought we were going to have with sharding and so it's a nice little circular journey. Um I'll stop there for a second and let the Yeah, I think I agree with you that it was inevitable but maybe for a bit different reason. We have a lot of very smart people in the industry like with PhDs many PhDs and uh whenever someone starts doing something quite exciting like scaling Ethereum there is like 200 people who know better how to do it. So we end up in a situation where we have like many different uh options from the mechanism design perspective and cryptography perspective of what is the best um how to scale Ethereum in the best way and then I think it's a bit tricky to force these people to talk to each other because everyone knows better there and then like I don't know for for some L2s like like ad tech like differentiation is quite visible at least from my perspective it's like privacy privacy versus no privacy I understand what that means and for summer to it's like you open the website it says oh we are like the best the most so much the one but not clear why so we are in a tricky situation I think yeah I think like I agree with both basically they just explain me and stuff But uh the way I see it is I think we've passed the point where it was kind of useful and enough. Now it feels like we have a hundred of them and some of them are just exact copies of others or just direct forks that just changes the name of the company and then they also raise and then they also launch a token and then they also dump the token. So maybe it's time to go back to the originals a bit. But uh yeah it was it was a fun experiment it seems and it worked so far at least kind of. Yeah. Yeah. The question if we can go back at all like if it's not not too late and like the whole ecosystem now is utterly fragmented and like there are no solutions for that essentially like based rollup like uh Lisa you've mentioned behind the scenes that based rollup doesn't make any sense actually for teams who is building it. Why you said that? I said it a bit differently. I know you asked should people build the based rollup or something and I said that okay in a perfect scenario no but okay if thinking like rationally having one based rollup it's like the most ethereum aligned rollup that you can come up with having one based rollup makes a lot of sense having many based rollups it's a philosophical question because maybe the the more alignment the better. But from like technical perspective if you think about like okay what can be built on base rollup from the UX and like me personally like I can't tell you what is the answer what should be built on um uh base rollup versus like uh some basic ze rollup unless it's something where like you want to have kind of sec as much security as possible Maybe if for example someone is building some infrastructure backup for the case of like nuclear war or something and you want to be sure that if everything is down in the world, you have this rollup flying somewhere in the space and backing up like some databases of your like citizens and some like financial coordination or some coordination at all. Maybe for this thing it makes sense to uh theoretically put it on base rollup because it will inherit Ethereum's uh decentralization to the largest extent. But if you ask me and if we think about like practical thing and not like theoretical thing, you have to do it private. You can't like put all critical infrastructure back up uh public uh it just won't happen. Can't you have privacy like uh in your rollup in your execution and uh just use Ethereum as a sequencer that's will give you livveness and security but then like you will have also your privacy I think it will be like it's it's possible to construct it but it will be like you know there is like appsp specific rollup it will be extremely appsp specific rollup that will be utilized It's only for this one particular use case because it will be very slow compared to all other rollups but it will be yes resilient and uh if someone is up for like building this I think they can take ad stick as like starting point like and then modify its sequencing to put it into base sequencing. It's not like a direct oneto one web requires solving some fun mechanism design tasks but yeah I have t question so what is the so in your ideal world of view so like how does the like the future of base rollup work you get one gigabase rollup that works nicely that is sequenced by L1 and what else do you need to make it perfect privacy yeah that's enough yeah let's make make a lot of sense. So, uh I just yeah mentioned uh centralized sequencing like I think people in this room like they we you all know like these debates around uh like one weak point not one but one of the major weak points in uh roll-ups today which is centralized sequencer essentially like rollup just can order transactions or censor them or suppress them or modify them any way they see fit. Okay, absolutely agree. I'm yeah simplifying here, but there is a point. So, uh how do you guys feel about centralizing sequencer for L2? Is it is it a problem? Is it really the as as uh as big problem as it as it seems? Before I answer this, I'm going to take a poll of the audience. Uh raise your hand if you know what the difference between a raise your hand if you know what a sequencer is at all. Okay, keep your hand up if you know the difference between a centralized and decentralized sequencer. Okay, still most people. Uh, keep your hand up if you could you think you could explain what a base rollup is. It's like two people. Okay, so we have some work to do. Um, so your your question was uh centralized versus decentralized. Yeah, if like if it's if it's uh actually worse than like trust assumptions significantly worse than the trust assumptions for the rollup. So like the point of a rollup uh of something that calls itself an L2 at least where I came from in initially uh was to inherit the security properties of Ethereum. Uh the idea is that you have Ethereum as a backup and so if your rollup for whatever reason goes down or tries to steal your money uh you can dispute uh the state update that tried to steal your money uh by going to the rollup contract on the you know Ethereum mainet and taking your money and leaving and you know potentially providing proof of the last you know valid state on a you know of that roll up where you had your in order to get your money out. Uh does that make sense so far? Absolutely. And so like in that case a centralized sequencer can for example censor you. Uh it it can you know screw with you in other ways but I if you have Ethereum as a fallback then it can't necessarily steal your money. Uh it can do things like that are kind of unexpected like for example you have your money in a lending pool on a layer 2 uh a or something. Who who hasn't who knows what how to lending pools and stuff? Okay, most of you guys understand how DeFi works great. So like um let's say I you know provide some collateral and then like people borrow it and then I I can't withdraw my money anymore, right? But like what the centralized sequencer could do is basically every time you go to try to withdraw your money out of the lending pool, they could borrow the money and then they could prevent you from uh withdrawing the money. And so there's like little side games they can play and and that actually limits your ability to then go and prove that you have money that you can withdraw on Ethereum mainet because Ethereum mainet's like your money is in this smart contract uh you know lending pool like I can't let you withdraw that. And so then you're actually kind of screwed. And so in order to get around that you might want to have multiple sequencers. And so that way one sequencer cannot uh by itself like play this game in order to freeze your money in the smart contract that would prevent you from then withdrawing on Ethereum that would allow you to have uh that as the backup. Does that all make sense? Did everybody okay? It make total sense. The question is how you enforce this like how you make actually roll up uh to use multiple sequencers. Yeah, they don't have any incentive as it as it happens. Or maybe they they are I don't know. So there's a couple reasons. So that's one of them. That's the security reason. The other one is uh a sort of fairness transaction ordering reason, right? if you you don't necessarily want to give one sequencer god mode uh powers in terms of uh ordering all of the transactions because there's arbitrage and it's essentially enshrining the me that you know we we call uh in one uh sequencer all the time. Um and so if it's decentralized then uh it's harder for one entity to necessarily claim all of that all the time. And so, uh, I looked it up. It's called Converge is the Athena, uh, system that's built using arbitrum. And so, part of the reason they're doing that, they're starting out having multiple sequencers so that, uh, they can, uh, have it be more fair so that one entity isn't necessarily getting all the me all the time. Makes sense. Uh maybe you you guys can me uh tell us a little bit about your systems you working on. Maybe Aztec what's your approach to sequencing essentially because you just recently released the sequencer. Yeah I think our intuition is maybe a bit different from what Amin has mentioned. Um for us it's like the question of okay what we are building first of all like we have like L2 uh it's a blockchain L2. So uh aside of everything we want it to be resilient, we want it to have livveness uh we want it to have all guarantees and uh what we are uh doing we have decentralized sequencer where by decentralized we do not mean several sequencers we mean like thousands of nodes uh as an endame uh running the sequencer because uh whatever happens in the world not only today but like in year in five years in 10 years we want to ensure that whatever happens in the world, the network uh continues running. uh we've seen I guess like a week ago a couple of weeks ago when the internet uh in France and uh Portugal went down and if you ask like a week ago people like is it possible everyone no no no no and we do not know like what happens next and maybe it is possible when the whole continent went down and what happens if uh all these servers run in the sequencer even if it's several sequencers I want that continent uh so for us we We want uh geographical decentralization. We want entity decentralization. We want the diversity between um professional operators, home uh node runners and so on and so forth because it uh provides the um guarantee that the network uh will last uh for a long time and for us it's a huge responsibility because it's not only that we are building network and uh we want it to last but we build a network and people build applications on this network and they trust us that this network will run because uh they want their applications to last for a long time. So it's a lot of uh responsibility for us and I guess last week uh we launched our uh first uh test net with decentralized sequencer. Um yeah and uh several hundred of uh sequencer runners uh joined within the first week. Um yeah. Is there a name? Sorry, just is there a name for the sequencer? For the project, you should have a catchy name. The name of the project is Aztec. The name of the sequencer is decentralized sequencer. How inventive the It's the first one. Finet. Is it fair? It wasn't called FET. No, no, it's decentralized sequencer. Okay, you should work on naming. I think it's incredible naming because it's unique. I mean, we do not have any other in the industry. I see what you did here. Okay. Decentralized sequencer. Let's call it this way. Okay. Yeah. True. I mean, if we had the first decentralized sequencer, then maybe we would also call it. But we have a centralized sequencer and it does not make sense to call it centralized sequencer. So that's another thing. So um yeah, what we do uh if we come back to the question just before that I want to mention something very briefly. I think all the decentralized like sequencing discussion comes down in my mind to the question of whether you can exit whenever you want which is kind of a very tricky one because today it is not possible for the most of the systems that we have which is really bad. I think we should do better. And then with ZKPS, you can actually achieve this kind of stuff like you can have built systems that you can exit the system even though the centralized sequencer is down or dead or screwed or stuff like that. So I think like we should focus more on these as an ecosystem. I know there are crazy people working on it but I don't think the efforts are enough. Why I say this is so we're building straa it's a ZK rollup which is another centralized sequencer but this time it's on Bitcoin. So the idea is you embed your layer 2ish data on Bitcoin itself and you also prove your execution. So you also post the proof as well for anyone who wants to verify if things are working correctly and nicely and um yeah it's a ZK roll up on Bitcoin. We're live on test net 4 of Bitcoin. Um and in addition to that the ma major problem is how are you going to move your funds from Bitcoin to the this layer. So currently existing solutions you give your money into some people and then beg them to not distill your money and this is the like current approach because there wasn't a better option. Now we have something a little bit better. Now we have an idea called bitvm that you can verify snarks in very interesting way using bitcoin scripts only and using this you can do one of trust assumption bridges which is like you only need one out of n to be honest where n entities are functioning for the bridge to continue to function all the time which is much better because then you don't trust three people out of five to not to steal your 20. Now you have one of 10 or one of 20 and only this one single one is enough. So I kind of prefer to link this with the trustlessness like the unilateral exit like can I exit whenever I want? The answer is no because if no one is honest then you're screwed. But um I think again like combining with this so for example if you were to do decentralized sequencing stuff then even though the machine is down people may still be able to exit or if you get new upgrades to Bitcoin which is easier said than done then we may have some other improvements as well but yeah the idea is we try to scale Bitcoin while you guys are doing good stuff on Ethereum and uh we shouldn't wait and we should ship what as possible against the limitations and maybe in the future the limitations we get rid of them like scaling L1 today like a popular idea. So yeah, that's it. What's the name of the project? It's called Citra like Citrus but make it Citra. I think it's one of the most interesting uh BTCs at this moment. I hope so. I hope so. Do you think uh we'll ever have zero knowledge up code on Bitcoin? So you guys can verify natively on Bitcoin? Let me ask this question differently. How many Bitcoiners do you need to murder uh in order to get a zero knowledge up code? I mean very much like a lot of them. Uh on the other side like there's some very solid resistance against us as well. But luckily you see the benefit of having a system that is permissionless like I can just build things and I don't really need to depend on anyone. So I think like as an industry we should always remember that and be grateful for that. Uh even though it causes a 100 rollups to launch which is most of them are exactly the same. It's still a net positive. So don't mind me on that. So just to drift away a little bit from technicalities maybe it's a like again philosophical question but do you think that retail which we all love and want to help and want to have a real impact do they really care about decentralization and things we discuss or we just live in our own bubble and just fix our own problems whom you call retail here the real people who uses use uh decentralized programmable systems You mean the spots in Asia or uh apart from this like uh I myself I I am a defi user. I use it for payments. I use it for financing like lots of different things but I'm not sure if I'm like not again just uh serve my own problems with with this super complex tech like we discuss a lot uh decentralization why it matters like how we fix it with technology how we fix social consensus around decentralization how we on board miners in proof of work world how we on board Ethereum foundation in Ethereum world and all this like super complex problems but do we really solve anything re real problems with decentralization specifically I'm not talking about privacy I think privacy has a real use case we all know that especially people who come from like uh some specific countries uh like myself uh but then like we ask yourself is it really like decentralization does it really solve a real problem for real people you know in web to world you have people who are happy with telegram and then you have people who will tell you telegram is not good. Let's go to signal. And then you have people who will tell you signal is not good. Let's go to matrix because it's decentralized on the protocol layer and this is like custom client and this is the way to go. These people who prefer decentralized on the protocol layer with matrix they will care the same people I don't know how many of them I know one who on boarded me into this application. These people will care about decentral decentralization of whatever they do including blockchain. Great. So we have three people now. You know one, I know two. I mean you you're probably the fourth. Um yeah I've I've used Matrix. Uh I'm with Signal. Yeah. I mean I mostly use Signal and some Telegram too. I mean it depends on like what you're using it for, right? So it's like uh to answer your question broadly, I think like people who appreciate decentralization are uh made not born. Uh like I lost all my money in Mount Gox once uh and then I started appreciating decentralization. So like if you lost all your money in BlockFi or Celsius or FTX like suddenly you care about decentralized finance, you care about the D in the DeFi. uh and you know like that's that's how it goes. I think um you know it'll follow the same path like wait until one of these centralized sequencer rollups uh gets shut down permanently or goes offline or censors somebody and then they'll say, "Oh, we should really think about how to get our money out of this thing. Uh we should take that pretty seriously." And so I think it goes in waves. Um, but you know, nobody cares until they do is like what Lisa was saying with the electricity going out in Portugal or something like your like I think people like us care obviously and if you count us as the retail then we care obviously on all this stuff that they built. If you like very honest maybe brutal opinion if you ask people that we're not mostly talking about they don't really care like and just a very simple example we say like everyone says oh Turkey has a great crypto adoption you know Turkey is great and stuff like that well Turkeykey's crypto adoption is great because everyone uses Binance and everyone just tries to buys USDT and the reason they do it is because banks really create problems for them and then what they do is they just put the money on on Binance and then one click swap, one click swap or whatever they want and then they get a notification saying like oh like dodgecoin increased 20% in the 24 hours and then they go see this and then they check it a bit and then they buy it and then they hold and you know gamble it a bit. So most of the people use it just like I don't really blame anyone for their um you know kind of being rich as soon as possible to be honest. It is what it is but actually we're now seeing more and more impact on what we do. We're now seeing more stable coin which every day we see any one of them and then we see more and more integrations like just like the fintech companies doing one by one by one and it actually helps us because now we can get around the ways that we're making using these stuff much much and much more practical which is a net win. But on the other side, you now got into got under the influence of more big companies and governments and presidents launching tokens. So do you consider this as a win? I don't know. Maybe it is good, maybe it is bad. I don't see it very nicely. But if you're looking compared to 5 years ago, 10 years ago, I guess it is getting better and better. So I think it's when kind of Yeah. Awesome. Yeah, I agree. We're getting there. I think I think president launching tokens is better than not launching to you know I much prefer this to like putting my friends in prison. Uh I mean yeah it is getting better at least in some in some regards. Okay let's drift away from like this from this topic like we have two excellent questions from audience they super technical so we don't have to talk politics just yet. So um yeah the good question about math like minor extracted value which is really the big thing in Ethereum you can say it's extortion you can say it's a business use case but like how how does uh this affect like how centralization of sequencer affects minor extracted value I think it's maybe for Lisa like you know all this stuff you were in Tao there is no math in Tao yeah correct I've in tao h I think it's the same problem of like u designing different rollups in general uh solving me is a very interesting mechanism design problem so uh we have uh we have options but in general yeah if you have one sequencer and this sequencer has access to all transactions I mean if I were sequencer it's reasonable to extract as MV as I can if uh by design I have an opportunity because if value can be extracted it will be extracted because I mean why not and then like I think for some rollups it's their uh business model because of rollup needs to earn money uh how you called it if you can be rich as early as possible why not or something like that what oh come again never mind um for uh some uh some rollups try I think it was Taiko's idea uh try to implement something close to me boost button L2 uh where like you have blog builders and they can extract uh MV and then K then can um like reallocate this ME through the whole uh chain of uh value creation and then again as Tao is like L2 uh you also can do potentially crosschain MV because it's a base rollup I think this was one of the main value propositions from design perspective of based rollup that you can do crosschain me but it's quite I would say technical and nuanced it is do we have time for last question from audience yes so it's it's it's for talip uh does the op return war affect you and how big are bitcoin rollup transactions okay just a very quick summary of what's going on today on Bitcoin world. Um, so the amount of data you can put on Bitcoin blockchain is very limited. Per block it's 4 megabytes. But then there are also very different variations of these and people in the last two years put a lot of JPEGs on Bitcoin and obviously not everyone liked it. Like having big butts in your blockchain is obviously not good. And then you know there are some different limitations of putting JPEGs and some of them are actually technically harmful for the blockchain and nodes itself. So and we released our white paper two weeks ago on how bridge works. It's a very solid root gold machine like we can talk about it if you want after this panel. Um, and at some point we do something tricky yet very clever that goes around some of the limitations and then some of the core days realized this on Bitcoin and then said like look you know what actually this a problem maybe we can fix this and it's a policy change not a fork or something but then the moment this idea came around and we were an example the moment anti-Jpec people went crazy like people started to debate and then threaten us and then went on the stages, read the, you know, Declaration of Independence, stuff like that. It it's just a whole another drama. Um, but yeah, so again, the same thing. It's a permissionless protocol that we're trying to do things just like Ethereum, just like Bitcoin. And because no one needs anyone's permissions, we don't really need anyone's opinion on that. And no, it doesn't affect us because we tried to get around it obviously and we found very clever ways to do things. And um you know we will do I think even better and on the transaction sizes per a couple bitcoin blocks we will fill 10% or 20% potentially of bitcoin block space which is quite some money if you're a minor. So but the problem is op return people didn't realize this yet. I hope they won't realize right after this talk as well because this is actually the thing that they're against it and uh we will see much funnier fights in the next weeks especially when we go mainet check your Twitter timelines it will be funny. Awesome. Thank you guys. I would continue this like for two hours but unfortunately we can't. Thank you so much for coming. So please give us Thank you. great finalist and have a great ethan thank you very much. So that was the first how do we how do we even describe what word can we use for that? I don't I maybe want to say nerd panel but maybe that's a little bit overkill. Uh technical panel. Thank you very much Collins. I appreciate that.