Systems Reliability Engineer - Core

About Us At Cloudflare, we are on a mission to help build a better Internet. Today the company runs one of the world’s largest networks that powers millions of websites and other Internet properties for customers ranging from individual bloggers to SMBs to Fortune 500 companies. Cloudflare protects and accelerates any Internet application online without adding hardware, installing software, or changing a line of code. Internet properties powered by Cloudflare all have web traffic routed through its intelligent global network, which gets smarter with every request. As a result, they see significant improvement in performance and a decrease in spam and other attacks. Cloudflare was named to Entrepreneur Magazine’s Top Company Cultures list and ranked among the World’s Most Innovative Companies by Fast Company. At Cloudflare, we’re not looking for people who wait for a polished roadmap; we’re looking for the builders who see the cracks in the Internet that everyone else has simply learned to live with. We value candidates who have the instinct to spot a "normalized" problem and the AI-native curiosity to create a solution using the latest tools. Our culture is built on iteration, leveraging AI to ship faster today to make it better tomorrow, while ensuring that every improvement, no matter how small, is shared across the team to lift everyone up. If you’re the type of person who values curiosity over bureaucracy, and that AI is a partner in solving tough problems to keep the Internet moving forward, you’ll fit right in. Hiring Locations: Lisbon, Portugal, London, UK About the Role We are looking for a Systems Engineer to architect, scale, and operate the distributed infrastructure that powers our global server fleets. You will drive automation and reliability work that keeps our systems fast and resilient at scale. Responsibilities Cloudflare is a system spanning the globe, on a mission to make the internet better, safer, and more powerful everyday. With this goal in mind, our product teams are responsible for deployed thousands of deployments at an ever increasing rate. • As an engineer on one of our Core platform teams, you'll be building the tools to help engineers deploy and operate the services that make Cloudflare work. Our mission is to provide a reliable, yet flexible, platform to help product teams release new software efficiently and safely. You’ll be building the private cloud that Cloudflare developers leverage to build Cloudflare itself. Core platforms we operate at Cloudflare include: • Kubernetes • Postgres, PgBouncer, and Stolon • Kafka • Zookeeper • Ceph & Rook • Developer tools, CI, and CD systems • Vault • Consul • Etcd • Temporal • Artificial Intelligence & LLMs You will • Architect, deploy, and maintain robust distributed systems, focusing on high availability, low latency, and horizontal scalability. • Optimise Performance: Analyse system bottlenecks, optimise kernel and network stacks, and fine-tune resource utilisation across global server fleets. • Drive Automation: Build and maintain internal tools and automation frameworks to streamline infrastructure deployment, configuration management, and monitoring. • Ensure Reliability: Participate in architecture reviews, capacity planning, and proactive system health monitoring to guarantee maximum uptime and resilience. • Collaborate Cross-Functionally: Partner closely with Security, Network Engineering, and Product teams to integrate infrastructure solutions smoothly across the entire stack. Desirable Skills, Knowledge, and Experience • Demonstrable professional experience building and managing large-scale distributed systems or Linux production environments. • Proficiency in at least one systems programming or scripting language (e.g., Go, Rust, C/C++, Python) with a track record of writing clean, maintainable code. • Deep understanding of Linux/Unix operating system internals (e.g., storage subsystems, memory management) and core networking protocols (TCP/IP, DNS, BGP). • Experience with configuration management and infrastructure-as-code tools (e.g., Ansible, Terraform, SaltStack). • Strong analytical and troubleshooting skills, with a methodical approach to diagnosing complex system-level failures. Bonus Points • Experience managing containerised workloads at scale using Kubernetes, Docker, or similar orchestration platforms. • Familiarity with CI/CD pipelines and automated testing strategies for infrastructure. • Contributions to open-source systems software projects or active participation in the broader systems engineering community. • Experience with any of our existing tooling, such as Kafka and Temporal • Good experience of harnessing AI to drive robust solutions What Makes Cloudflare Special? We’re not just a highly ambitious, large-scale technology company. We’re a highly ambitious, large-scale technology company with a soul. Fundamental to our mission to help build a better Internet is protecting the free and open Internet. Project Galileo: Since 2014, we've equipped more than 2,400 journalism and civil society organizations in 111 countries with powerful tools to defend themselves against attacks that would otherwise censor their work, technology already used by Cloudflare’s enterprise customers--at no cost. Athenian Project: In 2017, we created the Athenian Project to ensure that state and local governments have the highest level of protection and reliability for free, so that their constituents have access to election information and voter registration. Since the project, we've provided services to more than 425 local government election websites in 33 states. 1.1.1.1: We released 1.1.1.1 to help fix the foundation of the Internet by building a faster, more secure and privacy-centric public DNS resolver. This is available publicly for everyone to use - it is the first consumer-focused service Cloudflare has ever released. Here’s the dea