Systems Reliability Engineer - Core

Description

The company runs one of the world's largest networks, serving millions of websites and internet properties, from individual bloggers to SMBs to Fortune 500 companies.

The company speeds up and protects any internet application without new hardware, installed software, or code changes. Traffic routed through its global network gets faster and sees fewer spam and attacks, and the network improves with every request.

The company was named to Entrepreneur Magazine's Top Company Cultures list and ranked among Fast Company's World's Most Innovative Companies.

The team values people who spot problems others have accepted and who use the latest AI tools to build fixes. Work is iterative, and improvements are shared so the whole team benefits. Curiosity matters more than bureaucracy.

Hiring locations: Lisbon, Portugal, and London, UK.

This role is a Systems Engineer position focused on designing, scaling, and running the distributed infrastructure behind global server fleets. You will lead automation and reliability work that keeps systems fast and resilient at scale.

Responsibilities

• Work on a Core platform team building the tools that let engineers deploy and run the services behind the company, including the private cloud its developers use to build the company itself.
• Help product teams release software quickly and safely on a platform that is reliable but flexible.
• Work with platforms including Kubernetes, Postgres with PgBouncer and Stolon, Kafka, Zookeeper, Ceph and Rook, developer tools with CI and CD systems, Vault, Consul, Etcd, Temporal, and AI and LLM systems.
• Design, deploy, and maintain distributed systems that are highly available, low latency, and horizontally scalable.
• Find bottlenecks, tune kernel and network stacks, and adjust resource use across global server fleets.
• Build and maintain internal tools and automation for infrastructure deployment, configuration, and monitoring.
• Take part in architecture reviews, capacity planning, and ongoing health monitoring to maximise uptime and resilience.
• Work closely with Security, Network Engineering, and Product teams so infrastructure fits together across the stack.

Requirements

• Have professional experience building or running large-scale distributed systems or Linux production environments.
• Be proficient in at least one systems programming or scripting language, such as Go, Rust, C/C++, or Python, and write clean, maintainable code.
• Understand Linux and Unix internals, such as storage and memory management, along with core networking protocols including TCP/IP, DNS, and BGP.
• Have experience with configuration management and infrastructure-as-code tools such as Ansible, Terraform, or SaltStack.
• Troubleshoot complex system failures methodically, with strong analytical skills.
• Optional: experience running containerised workloads at scale on Kubernetes, Docker, or similar orchestration platforms.
• Optional: familiarity with CI/CD pipelines and automated testing for infrastructure.
• Optional: contributions to open-source systems software or active involvement in the systems engineering community.
• Optional: experience with the company's existing tooling, such as Kafka and Temporal.
• Optional: good experience using AI to build robust solutions.

Conditions

Applicants who reach the offer stage may be asked to attend an in-person interview at a the company office or hub. Details will be shared at that stage.

This role may involve access to information controlled under U.S. export laws, including the U.S. Export Administration Regulations. Any offer may depend on your ability to receive controlled software or technology without sponsorship for an export license.

Benefits

• The company's Project Galileo provides its tools at no cost to more than 2,400 journalism and civil society organisations in 111 countries since 2014.
• The Athenian Project, started in 2017, provides free protection to state and local government election websites, serving more than 425 sites across 33 states.
• The company's public DNS resolver, 1.1.1.1, is free for anyone to use and does not store client IP addresses.