Circle Innovation & Technology Culture

Describe a project you’re especially eager to tackle in the new year.

I’m especially excited about Multi-Proposer, a major evolution of Arc, the open Layer-1 blockchain we’re building at Circle. Arc combines a high-performance consensus engine with ethereum virtual machine-compatible execution, designed to provide scalable and reliable infrastructure for developers and financial applications. Today, each block in Arc is proposed by a single node. With Multi-Proposer, multiple nodes will propose in parallel — boosting throughput, censorship resistance and resilience against delays or manipulation.

Multi-Proposer primarily lives at the consensus layer, but we’re also introducing additional innovations to make multiple proposers possible. It’s a complex engineering challenge that requires coordination between components that traditionally operate one after another. By tackling it, we’re building a network that remains fast and reliable even under demanding or adversarial conditions. This project blends deep distributed systems theory with practical engineering, the kind of problem that makes building on Arc both challenging and deeply rewarding.

What technologies and/or practices is your team leveraging to tackle this project?

Our stack is built primarily in Rust, giving us safety and performance for consensus-critical code. We rely on Reth, the modular Ethereum execution client, and Malachite, a Byzantine Fault Tolerance consensus engine, to orchestrate Multi-Proposer logic. Arc coordinates consensus and execution through the standard EngineAPI interface. Within the consensus layer, Malachite ensures proposals are consistently ordered across the network, supporting both efficiency and fault tolerance.

On the practices front, we focus on reproducibility, correctness and disciplined engineering. Our agile workflow with Jira promotes iteration and fast feedback. Every change undergoes rigorous code review, continuous integration checks and extensive testing, from unit and integration tests to full end-to-end and system testing. These practices help ensure our releases remain reliable, secure and predictable.

How does this project tie into larger company goals?

Multi-Proposer advances Arc’s mission to provide a trusted foundation for real-world economic activity with blockchain infrastructure that is efficient, distributed and censorship-resistant. By allowing multiple proposers to operate at once, we eliminate single points of contention and create a fairer, more resilient consensus process.

Arc is also distinctive in that its native gas asset is USDC, enabling stable and predictable dollar-denominated transaction fees, which provides simplified user experiences and accounting for global businesses. This aligns perfectly with Circle’s broader mission of raising global economic prosperity through the frictionless exchange of value — a world where trillions in stablecoins and financial transactions happen natively on the internet. Arc is at the foundation of that future: a global platform that enables scale, speed and coordination across people, companies and even machines.