Gibraltar Testnet Sees External Operators Running Espresso Sequencer Nodes

Espresso Systems releases testnet 4 (Gibraltar), showcasing an integration with the Arbitrum technology stack

Espresso Systems
4 min readJan 25, 2024

Today, we are unveiling the fourth testnet of the Espresso Sequencer, Gibraltar. This testnet showcases a new integration with the Arbitrum technology stack and sees external operators running Espresso Sequencer nodes for the first time.

We’re excited to be supporting the Arbitrum ecosystem with a shared sequencer option that will provide Arbitrum technology chains with improved interoperability and decentralization, while maintaining the lightning-fast experience their users are accustomed to.

The Espresso Sequencer is a credibly neutral, fast-finality layer that any rollup can leverage for transaction ordering, data availability, and fast pre-confirmations. The sequencer protocol leverages HotShot consensus, enabling it to scale to thousands of nodes while still providing near-instantaneous pre-confirmations.

For this testnet release, we’ve been working closely with the Blockdaemon team who is managing external sequencer nodes for Gibraltar. We are thrilled to see Gibraltar become the first shared sequencer network running with external node operators.

This release is available to the public. The code we have developed to integrate with the Arbitrum tech stack is available on GitHub. As a part of this release, we have also published documentation that will enable developers and users alike to interact with Gibraltar and its integrated rollups.

If you are building a rollup, you can get started on your integration with the latest Espresso testnet here and reach out to collaborate with us here.

Gibraltar running on external node operators

We have partnered with Blockdaemon, a blockchain infrastructure provider, who is supporting us by deploying external sequencer nodes. They will be managing 4 sequencer nodes that are based in Europe and Asia. This collaboration sees the Espresso Sequencer make progress in decentralizing the network, and become more resilient and geographically distributed.

We’ll be hosting an AMA with the Blockdaemon team in our Discord on February 6, 2024 at 11 AM EST to share our progress in onboarding external node operators the Espresso Sequencer network. We’ll also hear from the Blockdaemon team about their experience as an Espresso Sequencer node operator. If you’re interested in running an Espresso Sequencer node, you’ll definitely want to attend.

Integration with Arbitrum stack

In September, we announced a partnership with Offchain Labs to explore decentralized, shared sequencing for Arbitrum technology chains. As a part of the Gibraltar testnet, we’re unveiling a new integration between the Espresso Sequencer and the Arbitrum technology stack.

Arbitrum technology chains will now have access to fast, decentralized shared sequencing. Arbitrum Orbit chains can integrate with the Espresso Sequencer today, and see how its preconfirmations are comparable to those of a centralized sequencer.

The integration of the Espresso Sequencer into the Arbitrum tech stack follows the announcement of our co-authored roadmap for decentralized Timeboost, a modified first-come-first-serve transaction ordering policy.

As we work with Offchain Labs on R&D efforts related to decentralized Timeboost, we are also exploring how the Espresso Sequencer can best serve as a neutral fast finality and interoperability layer for Arbitrum Orbit chains and the Arbitrum ecosystem. Another benefit of this integration is that it also gives the Espresso Systems and Offchain Labs teams an environment where we deploy decentralized Timeboost for testing.

Arbitrum Orbit chains can deploy their rollups on the Gibraltar testnet today by following the steps in our integration guide.

Caldera deploys Arbitrum rollup, Milan, integrated with Espresso Sequencer

Users and developers can submit transactions to the Milan rollup co-deployed with Caldera today. The Milan rollup is live and processing transactions, and users can easily interact with the rollup through their MetaMask wallet.

Developers can also deploy contracts to the Milan rollup by following the instructions listed in Caldera’s documentation.

AltLayer’s Arbitrum rollup, Kyoto, coming soon

AltLayer will also be releasing an Arbitrum rollup, called Kyoto, deployed on the Espresso Sequencer as a part of this public release. We will release more details on Kyoto when it is live and in production.

We’re excited to be working with the Caldera and AltLayer teams on deploying multiple rollups to the Espresso Sequencer!

Supporting shared sequencing for the Polygon zkEVM stack, OP Stack, Cartesi Stack, and Arbitrum technology chains

With the Arbitrum stack integration in Gibraltar, users can now submit transactions for rollups built on the Polygon zkEVM stack, Cartesi Stack, OP Stack, and Arbitrum technology chains. This now means that users of any rollup technology stack can enjoy the fast pre-confirmations the Espresso Sequencer enables.

If you’d like to try submitting transactions or deploying contracts to any of the integrated stacks on the Gibraltar testnet, you can head to our documentation site where we outline how you can get started. You may also build and run a local devnet of Gibraltar by following instructions in our GitHub.

Join the Espresso Ecosystem

The Gibraltar release follows our Cortado (testnet 3) release in September, 2023. Cortado was the first publicly available shared sequencer testnet, integrating with both the Polygon zkEVM and OP Stacks. Now, with the Arbitrum stack integration, we continue to support various rollup stacks and showcase how the Espresso Sequencer can provide credibly neutral, decentralized, shared sequencing for any number of rollups.

Be sure to follow along on Twitter/X and at our website for further updates on Gibraltar and our collaboration with Offchain Labs.

If you’re interested in deploying on the Gibraltar testnet, please get in touch with us here.



Espresso Systems

We are the lead developers of the Espresso Sequencer, which supports rollups with decentralization, scale, and interoperability.