Systems Engineer, Spectrum

• Join Spectrum within the Packet Processing team, which builds and operates the L3/L4 dataplane services sitting at the front door of Cloudflare’s global network. • Take shared ownership of a critical, high-scale Layer 4 reverse proxy that handles arbitrary TCP and UDP traffic. • Give customers DDoS mitigation, anycast performance, TLS termination, and global footprint for gaming servers, SSH, MQTT, custom protocols, and TLS-terminated services. • Work on an edge dataplane running across every Cloudflare colo, terminating and forwarding a very large volume of concurrent connections per second. • Help evolve Spectrum into the next generation of Cloudflare’s non-HTTP traffic platform. • Work close to the metal on a team that obsesses over performance, correctness, and reliability at massive scale. • Own what you build in production, including on-call and incident response. • Work from London on a hybrid basis, with the role also open in Austin, Texas.

• Bring experience building and shipping large-scale, reliable, highly distributed systems. • Bring strong programming experience in Go. • Bring a solid understanding of L3 and L4 networking including TCP, UDP, IP, connection state, NAT, anycast, and packet flows. • Work with Linux networking primitives such as sockets, eBPF, network namespaces, netfilter and nftables, and tc. • Design and integrate RESTful APIs and backend systems. • Operate what you build in production through on-call rotations, incident response, and root-cause analysis. • Reason about existing systems at scale, reading unfamiliar code, understanding hidden dependencies, and safely evolving software that has run in production for years. • Debug and optimise well, particularly around performance and connection lifecycle issues. • Communicate clearly in writing and in person, working across teams to land shared solutions.

• Bring familiarity with Rust, or the willingness to work in it. • Bring experience with TLS termination, PROXY protocol, or L4 and L7 proxies such as Envoy, HAProxy, or nginx stream. • Bring experience with ClickHouse, Kafka, or large-scale connection and flow analytics pipelines. • Bring experience with globally distributed KV or config-push systems. • Bring prior work on DDoS mitigation, anycast routing, L4 load balancing, or high-throughput edge network daemons. • Bring contributions to open source networking or proxy projects.

• Work on the Spectrum edge dataplane in Go, covering TCP and UDP connection acceptance and forwarding, TLS termination, PROXY protocol, connection accounting, and eBPF integrations. • Build the Spectrum control plane in Go, including application configuration APIs, provisioning, and the systems that push config globally to every edge machine. • Integrate Spectrum with Unimog for L4 load balancing, Magic Transit for IP transit, and Argo Smart Routing for accelerated origin paths. • Maintain operational excellence across analytics pipelines, observability, on-call, and incident response. • Pay down technical debt in a product with a long production history. • Help shape where Spectrum goes next as the L4 counterpart to the HTTP proxy stack. • Partner with the rest of Packet Processing, other Traffic Management teams, DDoS, DNS, Core SRE, and Edge SRE on problems spanning the whole Cloudflare stack.

We have used Cloudflare products ourselves, including Turnstile to protect apps from bots, so we know first-hand how solid their tech is, and that matters when you are thinking about where to work. With over $2.1 billion in annual revenue, 34% growth in Q4 2025, and $4 billion+ in cash reserves, Cloudflare is financially rock-solid and still growing fast. They operate one of the largest networks in the world, sit in front of roughly one in five websites, and are pushing hard into AI infrastructure and the agentic web. The scale of what they do is genuinely impressive; so many of the apps and services you use every day depend on Cloudflare without you even knowing it. Across Glassdoor, employees consistently highlight the great products, friendly and smart colleagues, positive working environment, and genuine flexible hybrid and work-from-home arrangements. They also offer unlimited paid time off and have a real focus on diversity and inclusion. We should be upfront, though: the Glassdoor rating sits at 3.4, and reviews are mixed. While the culture and people are widely praised, compensation competitiveness and slow promotion processes are recurring pain points. However, if you want to solve hard, Internet-scale problems at a company whose products you probably already rely on, Cloudflare is a brilliant place to do that.

• Take shared ownership of a product with massive existing scale while helping shape its next generation. • Work close to the metal on systems that handle every packet entering Cloudflare’s network. • Solve problems that span the entire Cloudflare stack alongside DDoS, DNS, and SRE teams. • Join a team that takes pride in shipping systems that just work for a very large fraction of the internet. • Choose between London and Austin as your base. • Join a company named to Entrepreneur Magazine’s Top Company Cultures list and ranked among Fast Company’s World’s Most Innovative Companies. • Contribute to public interest work including Project Galileo, the Athenian Project, and the 1.1.1.1 resolver.

Cloudflare is on a mission to help build a better Internet, running one of the world’s largest networks and powering millions of websites and Internet properties for customers from individual bloggers to Fortune 500 companies. Its Packet Processing team owns the L3/L4 dataplane services that receive, inspect, route, and forward every packet entering Cloudflare across every colo in the world, spanning Unimog, Magic Transit, Cloudflare WAN, and Spectrum. Fundamental to Cloudflare’s mission is protecting the free and open Internet: Project Galileo has equipped more than 2,400 journalism and civil society organisations across 111 countries with protection at no cost, and the Athenian Project has served more than 425 local government election websites across 33 states.