Sr. Site Reliability Engineer (UK)

Job Summary

The Senior Site Reliability Engineer is responsible for improving the reliability, scalability, security, and operational efficiency of Firstup’s business-critical, multi-tenant cloud platform. This role leads complex incident response and root-cause improvements, balancing immediate customer and production needs with durable, scalable solutions. Working closely with Engineering, Information Security, and Customer Success, the Senior Site Reliability Engineer helps build an operability culture that protects customers, reduces risk, and supports the continued growth of the platform.

Responsibilities

• Partner closely with application engineering teams to design, build and operate reliable, scalable and resilient production services.
• Work across both the application and infrastructure stacks, helping engineers identify and resolve reliability, performance and operational issues.
• Establish and drive SRE best practices, including service-level indicators and objectives (SLIs/SLOs), error budgets, operational readiness reviews and production reliability standards.
• Develop and maintain an SRE scorecard that measures service health, availability, resilience, observability, deployment quality and operational maturity.
• Lead initiatives to reduce mean time to detect, acknowledge and recover (MTTD/MTTA/MTTR) through improved telemetry, automation, diagnostics and incident-response practices.
• Own and evolve the monitoring and observability strategy across metrics, logs, traces, application performance monitoring, database monitoring, real-user monitoring and synthetic testing.
• Improve end-to-end visibility by correlating application requests, infrastructure performance, database activity, dependencies and customer-impacting symptoms.
• Lead and participate in incident response, facilitate effective technical investigations and ensure post-incident actions result in measurable reliability improvements.
• Identify recurring operational work and eliminate toil through automation, self-service capabilities, standardized tooling and platform improvements.
• Improve alert quality by establishing actionable alerts, service ownership, escalation paths, runbooks and automated remediation where appropriate.
• Conduct capacity planning, performance engineering, failure-mode analysis and resilience testing for critical services.
• Define production-readiness requirements for new services and major changes, including monitoring, alerting, scaling, security, rollback, backup and disaster-recovery expectations.
• Partner with engineering teams to improve deployment safety through progressive delivery, automated validation, health checks and effective rollback mechanisms.
• Provide technical leadership, mentoring and practical guidance that raises the operational maturity of engineering teams without creating dependency on the SRE function.
• Communicate reliability risks, operational trends and improvement priorities clearly to engineering and business stakeholders.
• Participate in on-call rotations, driving restoration and repair of service-impacting issues.

Minimum Qualifications

• BS or MS in Computer Science (or equivalent diplomas and/or certifications) with 8+ years of relevant experience.
• Strong experience in Site Reliability Engineering, production engineering, platform engineering or a comparable role supporting large-scale, distributed, customer-facing applications, ideally in a multi-tenant environment.
• Demonstrated ability to troubleshoot across the full technology stack, including application code, APIs, containers, Kubernetes, cloud infrastructure, networking, databases and third-party dependencies.
• Strong experience operating production workloads in AWS and Kubernetes-based environments.
• Strong understanding of observability principles, with hands-on experience in monitoring, logging, distributed tracing, and APM. Deep practical expertise with Datadog is required.
• Proven experience defining and implementing SLIs, SLOs, error budgets, reliability scorecards and operational health metrics.
• Experience diagnosing application latency, resource contention, database performance, dependency failures and complex distributed-system behavior.
• Strong automation and software-engineering skills using one or more languages such as Python, Go, Java, JavaScript/TypeScript or similar.
• Experience with infrastructure as code, including Terraform, as well as CI/CD pipelines, configuration management, and automated deployment practices.
• Strong ownership mindset with the ability to independently identify reliability gaps, prioritize improvements and drive initiatives through completion.
• Excellent written and verbal communication skills, including the ability to explain complex production issues and reliability risks to both technical and non-technical stakeholders.
• Willingness to participate in an on-call rotation and continuously improve the on-call experience through better tooling, documentation and automation.