Systems Engineer (London)

About OpenCoreOS

• We're building the first open-source "Thin Ledger", designed to replace legacy core systems with a Golang-based, Protobuf-defined, event-driven platform powered by Kafka, Redis, and multi-region CockroachDB/YugabyteDB.

• Our platform is AI-native from the ground up: autonomous SRE agents, AI-generated runbooks, and everything-as-code—from policies to infrastructure definitions.

• We're mission-critical by default, targeting five-nines uptime and multi-region failover for regulated institutions.

• We work openly and fast, and colocate in Huckletree, Liverpool St, London for in-person collaboration, supported by async-friendly workflows.

What you'll do 🚀

The Core Ledger Engine

• Implement distributed consensus for replicated state across nodes

• Design deterministic state machines where identical inputs always produce identical outputs

• Build two-phase commit protocols for complex multi-party settlements

• Create type-safe financial primitives that make entire classes of bugs impossible

• Optimize hot paths for microsecond latency with cache-aware data structures ️

Transaction Processing

• Architect atomic transaction chains (linked transfers that all succeed or all fail)

• Implement checkpoint/rollback semantics for complex financial workflows

• Build idempotency guarantees for exactly-once processing in distributed environments

• Design constraint systems for balance validation that never permits overdrafts or invalid states ️

High-Performance IO & Networking

• Design storage engines using direct IO and modern kernel interfaces for predictable latency

• Implement zero-copy networking paths to minimize memory bandwidth overhead

• Build async IO subsystems that saturate hardware without blocking consensus

• Optimize for kernel bypass and minimizing syscall overhead on critical paths

⚡ Build next-gen infrastructure Systems Engineer 2

• Support multi-cloud deployment with consensus-based failover

• Build observability and audit systems for regulatory compliance

• Create tooling for deterministic replay and debugging of production issues

Who you are

• Systems programmer at heart. You understand memory layouts, cache lines, and why allocation on the hot path matters.

• Distributed systems practitioner. You know the difference between Raft and Paxos, understand why linearizability matters, and have opinions on consensus protocol trade-offs.

• Correctness-obsessed. You write code that handles every edge case. You think about invariants, prove properties, and design systems that are correct by construction.

• Low-level thinker. You're comfortable reasoning about concurrency without locks, understanding why single-threaded event loops can outperform multithreaded alternatives, and optimizing for predictable latency.

• Security mindset: Understanding of secure coding practices and experience with high compliance systems

• Ownership mindset: You thrive on autonomy, figure things out proactively, and excel at thoughtful prioritization

• Exceptional communicator: Skilled at translating technical concepts across teams

• AI-native engineer: You naturally integrate AI into your workflow—actively using advanced AI tools

Nice-to-haves

• Fintech experience: Knowledge of financial transaction flows or HFT / T1 core banking

• Systems programming language experience: Low-latency systems built using Rust

Why join us?

• Massive impact: Transform how T1 banks handle billions of transactions daily—on a truly open platform.

• High-caliber team: Join a small team of exceptional engineers who value both speed and stability.

• AI-native workspace: Experience an AI-first environment with LLMs integrated into every tool.