Senior Customer Reliability Engineer

Description

The company runs one of the largest networks in the world, serving everyone from individual bloggers to SMBs and Fortune 500 firms, and it speeds up and protects web applications without hardware, installed software or code changes.

Banks, governments, media companies and health systems now run critical services on the network, so reliability for those customers is a core product concern.

The Customer Reliability Engineering team applies SRE methods to the systems customers run on the network. Members work with Product Engineering on product and tooling changes, and the team is building its work around AI-assisted diagnostics.

The team is small enough that you will see your work reach customers directly, and its culture favours curiosity over bureaucracy.

Responsibilities

• Work as both a rapid response engineer and a proactive engineer. Both parts of the role are equally important.
• Respond to high-severity, cross-layer, complex customer issues. Reproduce the defect, find the root cause across the company's infrastructure and the customer's stack, drive the fix with Product Engineering, and confirm that it works.
• Own the hardest customer issues from first signal to confirmed resolution, and lead deep debugging across edge, network, DNS, transport, APIs, applications and customer configuration.
• Build, with Product Engineering and platform teams, telemetry, detectors and diagnostic tools that find customer problems early and scale across hundreds of customers. Write automation that cuts toil for Customer Support.
• Analyse support and telemetry data across the customer base to find systemic risks. Define customer reliability metrics such as error rates, resolution times and repeat-contact rates, and drive them down.
• Build and work with AI agents that pre-diagnose incidents, pull relevant logs and configuration, and propose fixes backed by linked evidence. Deploy them internally and measure whether they make engineers faster.
• Write postmortems that other engineers rely on, and represent the customer reliability view in engineering syncs and incident reviews.
• Manage escalations with clear ownership and timely updates. Partner with Product Engineering on fixes, workarounds and configuration changes.
• Raise the technical level of Customer Support through pair debugging, knowledge transfer, runbooks and shared tooling.
• Keep current expertise across the product portfolio, including edge networking, DNS, CDN, WAF, DDoS mitigation, Zero Trust, Workers and the developer platform. Anticipate customer impact from new releases, and become a go-to expert in one or more areas.
• Examples include tracing uneven latency from a single point of presence through BGP routing, diagnosing a recurring WebSocket disconnect tied to a release, and helping a government customer's SRE team tune DDoS and WAF settings during an attack.

Requirements

• At least 5 years of hands-on experience in site reliability, escalation, systems engineering, or a similar deeply technical support or operations role, with at least 2 years in customer-facing environments.
• Understanding of TCP/IP, the OSI model, IPv4 and IPv6 addressing, subnetting, routing and switching.
• Working knowledge of DNS, HTTP/S, TLS/SSL, SMTP, SNMP and NTP.
• Understanding of BGP and OSPF, including path selection and route propagation.
• Understanding of firewall concepts: stateful and stateless inspection, rule sets, NAT and ACLs.
• Understanding of IPSec, SSL/TLS tunnels and GRE, plus Zero Trust architecture, network segmentation and modern security models.
• Hands-on use of packet capture and analysis (Wireshark, tcpdump), log tools (Kibana, Elasticsearch), Grafana dashboards and distributed tracing.
• Strong scripting in Bash and Python, with a record of shipping tools that improve reliability and reduce toil.
• Experience with incident management, postmortem practice, and SLO and SLI-based reliability.
• Clear written and spoken communication, able to explain complex technical issues to engineers, leadership and customers.
• Comfort owning ambiguous, cross-layer problems and staying calm during high-severity incidents.
• Desired: experience in SRE, DevOps or platform engineering with direct accountability to customers.
• Desired: deep knowledge of L3 and L4 network infrastructure and of L7 protocols, including DNS, HTTP and WebSocket.
• Desired: expert use of Linux command-line tools such as curl, dig, git, traceroute, mtr, strace and ss.
• Desired: analysing large datasets with SQL, PromQL or similar.
• Desired: familiarity with CI/CD pipelines, infrastructure as code (Terraform, Pulumi) and container platforms (Kubernetes, Docker).
• Desired: a record of building internal tools or diagnostic utilities that measurably improved team efficiency.
• Desired: technical leadership, such as mentoring engineers, leading cross-team work and influencing outcomes without formal authority.
• Desired: experience applying AI or ML to production engineering or operations workflows.
• Desired: comfort working directly with enterprise customer engineering teams, including on calls during incidents.
• Bonus: active use of the company as a practitioner.
• Bonus: hands-on experience with Workers, Pages, R2, D1 or other developer platform services.
• Bonus: cloud networking and security experience on AWS, Azure or GCP.
• Bonus: web programming in HTML and JavaScript, and regular expressions.
• Bonus: chaos engineering or formal reliability frameworks, such as Google SRE principles.
• Bonus: running non-HTTP services such as email, authoritative or recursive DNS, FTP or SSH.

Conditions

Location: Lisbon, Portugal or London, UK.

For Portugal-based hires, the estimated annual salary is €61,000 to €84,000.

The final offer will include time exemption in line with applicable law and collective bargaining agreements.

The role is eligible for the company's equity plan.

On-call duty covers high-severity incidents in a global rotation that includes weekends.

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

The role may require access to information controlled under U.S. export control laws, including the Export Administration Regulations. Any offer may be conditioned on your authorisation to receive controlled software or technology without sponsorship for an export license.