We’re bullish Ethereum L2s.
L2s are successfully taking execution off-chain and horizontally scaling Ethereum. It’s clear from ever-increasing metrics that users enjoy the lower fees and improved user experience provided by these protocols. Transaction count and total value locked have also grown exponentially over recent years (see L2BEAT). The speed of innovation around the L2 landscape is unprecedented, with new solutions coming to market every week.
But, Ethereum didn’t have the coordination layer to ensure that these new L2s could seamlessly interoperate with each other. Currently, users must move between fragmented execution environments, fracturing the composability they’re accustomed to on the Ethereum L1. Users also face long times for simple tasks such as bridging, which can take several minutes for deposits and up to several days for withdrawals.
Coordinated sequencing and fast trustless message passing using zk-proofs are foundational building blocks towards improved composability. Ethereum Foundation researcher Justin Drake recently highlighted how these approaches solve rollup fragmentation, thus supporting a more unified scaling roadmap for Ethereum.
Our mission at Espresso is to maximize the value layer-2 rollups capture, while ensuring they optimize the ability to satisfy user requests. This should be seamless even when users wish to interact with multiple rollups simultaneously and interdependently. This is why we are coordinating development efforts with Polygon Labs, the developers of Polygon PoS, Polygon zkEVM, Polygon CDK, and the AggLayer. The focus of this work will be on the development of the AggLayer and how it will be supported, and enhanced, by Espresso’s sequencing marketplace and fast-finality layer.
The AggLayer can support faster, more secure bridging and near-synchronous composability between rollups. It does so through enabling rollups to securely pass messages to each other while ensuring that the inputs on one chain are valid outputs from another chain. Multiple rounds of messages can be passed before settlement on Ethereum. Transactions on each of the rollups may be dependent on these messages. Unlike prior “bridging” solutions, these transaction dependencies are guaranteed by the AggLayer without trusted intermediaries. When a rollup creates a message output destined for other rollups it will also create a validity proof of its correctness. If it could do so in real time, the receiving rollup could simply verify the proof while interpreting the message; however, the state of proving is not sufficiently fast yet. The beautiful insight of the AggLayer is that the creation of these proofs can be delayed until all interdependent rollup blocks are created, and then aggregated and verified jointly at the same time the blocks are posted and settled on Ethereum.
However, while the AggLayer provides security for cross-rollup message passing, these interdependent rollup blocks don’t magically manifest on their own — that requires coordination. This is what the AggLayer leaves up to an emergent coordination layer. Enter Espresso.
Espresso provides a sequencing marketplace through which specialized service providers (sequencers) can purchase the right to coordinate the block construction of multiple rollups at the same time. This right may be short-lived or longer-term and can easily change hands. The sale proceeds go directly to the rollups involved and only if they clear a minimum price set by each rollup. Sequencers that can generate surplus value through coordinating block construction for multiple chains are best positioned in the market to successfully clear these prices, above and beyond what rollups can gain sequencing on their own. One way to do so for AggLayer-compatible rollups is to fill this key coordination role that AggLayer-secure message passing requires. Additionally, Espresso provides a fast confirmation service, HotShot, that allows users to know the results of their cross-rollup transactions before Ethereum settlement (aka fast finality).
In short, these technologies significantly improve Ethereum’s user experience and security when leveraged together. Our teams will be working together to maximize the compatibility of Espresso and the AggLayer, ensuring that all Ethereum L2s will be able to leverage both technologies for improved composability.
We’ll be updating the community on our plans to further integrate the Polygon technology stack with Espresso.
We will post regular updates on our progress in this thread on the Polygon community forums. We will also be hosting a Twitter Spaces with the Polygon Labs team on [date] to discuss next steps related to these development efforts.
If you are a rollup or application developer interested in leveraging the AggLayer and Espresso, you can get in touch with us here.
Espresso will be decentralizing the set of nodes running HotShot consensus in its upcoming testnet, Cappuccino, to be released later this month. This is an important milestone on Espresso’s journey of steadily growing the operator set leading up to mainnet — with HotShot’s ultimate goal being to encompass the distribution and staked capital of the entire Ethereum validator set.
In our latest testnet, Gibraltar, we partnered with Blockdaemon, which ran 4 HotShot nodes across Asia and Europe, in addition to those operated by Espresso Systems. With Blockdaemon’s support, Espresso was the first platform for rollup sequencing running with external node operators on testnet.
Deploying Espresso testnets on multiple nodes run by a diverse group of node operators is an important step towards readying the Espresso infrastructure for a production launch. As part of this, our next testnet, Cappuccino, will be run on 100 nodes that are geographically distributed across 6 continents.
Espresso has two core components. The first is a sequencing marketplace, where rollups sell slots to participating sequencers. The second is a consensus protocol that functions as a finality layer. The finality layer supports the marketplace and can also be leveraged independently.
A sequencer participating in the Espresso marketplace may bid for the opportunity to sequence blocks for multiple rollups at once — allowing them to facilitate cross-rollup activity, among other advantages. A rollup may have a default sequencer, which produces blocks for the rollup in the event that the sequencing opportunity isn’t sold. The marketplace maximizes economic efficiency within the entire rollup sequencing space and the value that rollups are able to capture..
The finality layer of Espresso is powered by HotShot. This is a BFT consensus protocol that provides users (or external entities including bridges, exchanges, etc.) with fast preconfirmations, or assurances that transactions will not be reversed, and will eventually be reflected on the Ethereum L1. HotShot is an optimistically responsive network, which means it can produce blocks as quickly as the network allows and reach finality within seconds, while scaling to thousands of operators. Expanding and diversifying the HotShot operator set in Cappuccino will help us continue to push the envelope on Espresso’s performance and security.
In February, we announced an open application process for node operators interested in running HotShot nodes for the Cappuccino testnet. After engaging with over 600 node operators, we were able to select 10 operators who will be running HotShot nodes for Cappuccino: Blockdaemon, Figment, Informal Systems, KudasaiJP, LinkPool, Nethermind, P2P.org, Sub7, Unit 410, and ZKValidator.
In this selection process, we prioritized operators in a range of locations to improve geographical diversity of the network and could support several cloud and bare metal environments. We also decided to work with experienced and highly technical operators who will help us to further define our node operator onboarding process and industry best practices. This is crucial as we look to create a smooth onboarding process for future operators, including those who join the HotShot network when it becomes fully permissionless.
These Cappuccino operators will collectively run 100 HotShot nodes for the testnet, spanning six continents.
With Cappuccino, Espresso will be the first platform for shared sequencing run on a distributed set of over 100 nodes. This paves the way to a credibly neutral decentralized network that will support rollup interoperability and security, while maintaining high performance.
We’re looking forward to running the Cappuccino testnet with our partners and building the supporting infrastructure to create a united Ethereum. If you’re a rollup interested in deploying on Espresso, please get in touch with us here.
We’re grateful for the time and effort contributed by our partners in support of the Cappuccino testnet, especially those who participated in the open call for node operators. Please note that although we will not be able to respond to all applicants individually, we will share progress updates and selection decisions via Twitter/X and in our Discord server via the #node-operators-updates channel. We will continue to update the recommended technical specifications for running a node in our documentation.
Partnering with 10 node operators to decentralize Espresso’s Cappuccino testnet
Espresso will be decentralizing the set of nodes running HotShot consensus in its upcoming testnet, Cappuccino, to be released later this month. This is an important milestone on Espresso’s journey of steadily growing the operator set leading up to mainnet — with HotShot’s ultimate goal being to encompass the distribution and staked capital of the entire Ethereum validator set.
In our latest testnet, Gibraltar, we partnered with Blockdaemon, which ran 4 HotShot nodes across Asia and Europe, in addition to those operated by Espresso Systems. With Blockdaemon’s support, Espresso was the first platform for rollup sequencing running with external node operators on testnet.
Deploying Espresso testnets on multiple nodes run by a diverse group of node operators is an important step towards readying the Espresso infrastructure for a production launch. As part of this, our next testnet, Cappuccino, will be run on 100 nodes that are geographically distributed across 6 continents.
Espresso has two core components. The first is a sequencing marketplace, where rollups sell slots to participating sequencers. The second is a consensus protocol that functions as a finality layer. The finality layer supports the marketplace and can also be leveraged independently.
A sequencer participating in the Espresso marketplace may bid for the opportunity to sequence blocks for multiple rollups at once — allowing them to facilitate cross-rollup activity, among other advantages. A rollup may have a default sequencer, which produces blocks for the rollup in the event that the sequencing opportunity isn’t sold. The marketplace maximizes economic efficiency within the entire rollup sequencing space and the value that rollups are able to capture..
The finality layer of Espresso is powered by HotShot. This is a BFT consensus protocol that provides users (or external entities including bridges, exchanges, etc.) with fast preconfirmations, or assurances that transactions will not be reversed, and will eventually be reflected on the Ethereum L1. HotShot is an optimistically responsive network, which means it can produce blocks as quickly as the network allows and reach finality within seconds, while scaling to thousands of operators. Expanding and diversifying the HotShot operator set in Cappuccino will help us continue to push the envelope on Espresso’s performance and security.
In February, we announced an open application process for node operators interested in running HotShot nodes for the Cappuccino testnet. After engaging with over 600 node operators, we were able to select 10 operators who will be running HotShot nodes for Cappuccino: Blockdaemon, Figment, Informal Systems, KudasaiJP, LinkPool, Nethermind, P2P.org, Sub7, Unit 410, and ZKValidator.
In this selection process, we prioritized operators in a range of locations to improve geographical diversity of the network and could support several cloud and bare metal environments. We also decided to work with experienced and highly technical operators who will help us to further define our node operator onboarding process and industry best practices. This is crucial as we look to create a smooth onboarding process for future operators, including those who join the HotShot network when it becomes fully permissionless.
These Cappuccino operators will collectively run 100 HotShot nodes for the testnet, spanning six continents.
With Cappuccino, Espresso will be the first platform for shared sequencing run on a distributed set of over 100 nodes. This paves the way to a credibly neutral decentralized network that will support rollup interoperability and security, while maintaining high performance.
We’re looking forward to running the Cappuccino testnet with our partners and building the supporting infrastructure to create a united Ethereum. If you’re a rollup interested in deploying on Espresso, please get in touch with us here.
We’re grateful for the time and effort contributed by our partners in support of the Cappuccino testnet, especially those who participated in the open call for node operators. Please note that although we will not be able to respond to all applicants individually, we will share progress updates and selection decisions via Twitter/X and in our Discord server via the #node-operators-updates channel. We will continue to update the recommended technical specifications for running a node in our documentation.
In 2021, we saw the first layer-2 rollups launch on Ethereum, focusing on scaling transaction throughput without sacrificing sovereignty, security, and decentralization. These systems have grown substantially in usage, even overtaking the Ethereum base layer in some key metrics. As this trend continues, our mission is to ensure that the growing number of rollups can continue to unlock new use cases without needing to give up decentralization, composability, and credible neutrality.
To accelerate this mission, we have raised $28 million in our Series B funding round. We’re excited that a16z crypto has led the round, joined by Polygon, Taiko, o1Labs, StarkWare, Offchain Labs, and core contributors and strategic investors from over 30 notable ecosystem projects — spanning rollups, L2 infrastructure, interoperability, and more. We are excited to work closely with these innovative partners, who are equally motivated to ensure that layer-2 protocols remain decentralized and interoperable.
This additional funding will help us continue product development, meaningfully invest in the broader rollup ecosystem, and set the stage for the community to ultimately operate and govern Espresso as a fully decentralized, credibly neutral public good for all L2s, from based rollups to validiums. We’ll be hiring aggressively to build out our team and expand our efforts. If you are a builder wanting to support the dream of a united Ethereum, please get in touch with us.
Espresso is more than just a shared sequencer, consensus protocol, or tool to facilitate interoperability between rollups — Espresso is a marketplace for shared sequencing, where rollups can sell the right to build their blocks to proposers who bid for these rights. Proposers can also bid on multiple rollup blocks to become shared proposers for multiple chains at once, which allows them to facilitate cross-chain activity. Anyone can participate in this marketplace, including L1 proposers and rollup DAO-appointed sequencers. Rollups that don’t want to worry about sequencing can also simply rely on Espresso to handle it for them.
Espresso’s HotShot finality gadget also offers lightning-fast finality on proposed blocks, ensuring that rollups don’t need to compromise on the experiences that their users are accustomed to. This finality is economically backed by both Espresso stakeholders and Ethereum restakers, potentially scaling to the entire Ethereum validator set, and provides assurances to users that their transactions will be finalized on the L1. Overall, we are building Espresso to be a one-stop solution for rollups to increase utility for their users through improved safety, liveness, and interoperability, while being compensated for the value they create and maintaining their sovereignty and autonomy.
This is an exhilarating time to build and innovate on Ethereum. We remain committed to Ethereum’s rollup-centric roadmap, and are more enthusiastic than ever about its ability to bring real users on-chain. We’re so grateful for the support we’ve received from our investors, partners, and the broader community. Onwards!
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