Releasing Espresso Testnet 1: Americano

Espresso Systems
3 min readNov 28, 2022

The Espresso Sequencer is a system designed to decentralize layer-2 (L2) scaling solutions. Today, we are releasing our first milestone in our development of the Espresso Sequencer: Espresso Testnet 1 — Americano.

Americano is our first demonstration of HotShot, an optimistically responsive consensus protocol underpinning the Espresso Sequencer that delivers Web2 performance with Web3 security. Our benchmarking and profiling of Americano establish a baseline of performance and precisely pinpoint performance bottlenecks for which we have plans to address in our future releases.

Though this release does not yet integrate the more advanced techniques on our roadmap to scale throughput, it already achieves a high baseline of performance in “good” network conditions. In our benchmarks, we measured throughput in network configurations of 10, 100, and 1,000 nodes with fixed stake distributions. Nodes were ECS instances with 4 GB memory and 2 CPU cores. The leader instance and centralized broadcast server were m6a.xlarge EC2 instances with 4 CPUs and 16 GB memory.

A throughput of 2598 kb/s maps to 10,000–20,000 ERC-20 transfers or 700+ CAPE transactions per second.

As a note, we also experimented with randomized committee sampling: on 1,000 nodes we limited the voting nodes to 100 and got a small but unsubstantial improvement to 284 KB/s. Even without committee sampling, we believe our initial HotShot benchmarks are a strong starting point.

Explore Americano

We’re excited to be sharing this key milestone with our community and invite enthusiasts and developers to get involved by checking out the code and sharing your thoughts.

This first testnet is an internal testnet, meaning it is not currently persistently deployed for public participation. If you are interested in becoming a validator for future Espresso Sequencer testnets and our mainnet release, you can stay tuned for updates by joining our Discord, following us on Twitter, and reach out to us here.

Along with this release, we’ve made the HotShot and espresso repos publicly available along with several additional utility repos. Together, these form the entirety of the Americano testnet, integrating the Espresso ledger with HotShot. We look forward to engaging with you on Discord and on Twitter!

What’s Next

Americano is just our first public release of the Espresso Sequencer.

Americano leverages a centralized network architecture to exploit the benefits of optimistic responsiveness. As a reminder, on account of this property, a centralized architecture helps increase throughput in optimistic conditions, but does not impact safety! With our next testnet, Doppio, we plan to further optimize the optimistic path (e.g., with load-balancing, parallelism, and even higher-bandwidth centralized servers) while integrating this with a robust gossip-based fallback path, which helps to retain liveness in pessimistic conditions. We will also integrate a data-availability mechanism to move data (i.e., full block) dissemination off the critical path of consensus.

The Doppio testnet will also take the first steps toward supporting live rollups. If you are working on a zk-VM or optimistic rollup and interested in leveraging the Espresso Sequencer to decentralize your layer-2 scaling solution, please reach out to us here.

There is still much to come. Over the upcoming weeks, we will be sharing more details on our approaches to key issues like data availability, rollup decentralization, and acceleration of proving. We will also be releasing a formal paper on HotShot consensus. Stay tuned!



Espresso Systems

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