Sr. Platform Engineer

About the job About Onedome We're a UK fintech building high-throughput digital infrastructure for the mortgage and property space. Recently acquired Trussle. We're taking our platform to the next level: fully automated, self-healing, observable, and built to handle real traffic spikes (we have a TV launch coming up). The role You'll be our senior platform engineer. Not a traditional ops role. You'll treat infrastructure as a product, build the internal developer platform our engineers deploy through, and bring SRE discipline into the application tier when it's needed. You won't have a platform team to lean on. You'll be building that capability. We know exactly what we need. What You'll Do Own 5 AWS accounts across the organisation (QA, Prod, Infra, plus two others) Architect and maintain infrastructure as code with Terraform. Replace the click-ops that's still around Stand up CI/CD pipelines engineers actually want to use. Blue/green and canary where it makes sense Run releases reliably and reduce key-person risk on the deploy process Set up monitoring, alerting, and incident response so we catch issues before customers do. Define SLIs and SLOs that map to real user journeys Lead incident response as the primary infra responder. Run blameless post-mortems Patch and harden the platform. We're a fintech, this matters. IAM least privilege, secrets management, vulnerability scanning, MFA enforcement Lead infrastructure work for the TV launch: traffic spikes, autoscaling, capacity planning, runbooks Partner with backend engineers when production issues cross into the app tier. JVM tuning, connection pools, async patterns, memory leaks Architect multi-region DR. Drive the platform toward self-healing Optimise cost across DynamoDB, Lambda, and the wider AWS footprint Set architectural guardrails with tech leads and SWEs. Mentor engineers as the platform capability grows You must have 6+ years hands-on AWS in production (VPC, IAM, EC2/ECS/EKS, Lambda, S3, CloudFront, Route53, RDS, DynamoDB, SQS) Production Terraform (Terragrunt a plus). Multi-environment state management Production Kubernetes and Docker. EKS specifically Strong CI/CD experience: GitHub Actions, GitLab, Jenkins, or ArgoCD. GitOps practices Strong infrastructure security: IAM least privilege, secrets, patching, vulnerability scanning, MFA enforcement Observability from scratch: CloudWatch, Datadog, Grafana, Prometheus, OpenTelemetry, or ELK Solid backend competency in Java (Spring Boot), Python, or Node. Understanding of JVM, concurrency, async systems Comfort being the senior infrastructure person. Self-directed, opinionated, disciplined about documentation B2/C1 Level English Nice to have Fintech or other regulated industry experience DynamoDB at scale (we run many tables with PITR and S3 exports, Lambda-driven daily incrementals) AWS cost optimisation track record Past experience as a first infrastructure hire at a small team Building internal developer platforms or self-service tooling AWS DevOps Pro, Solutions Architect Pro, or CKA Service mesh experience (Istio, Linkerd) and DevSecOps practices Firebase or GCP exposure (we have a small footprint there) What You Won't Get From Us A platform team to lean on. You'll be building that capability Click-ops everywhere. You'll be replacing what exists with IaC Ambiguity about the work. We know exactly what we need Working setup UK working hours. Fully remote across the EU Tooling: Microsoft 365, Teams, Planner, Nuclino, GitHub aws-vault with MFA enforcement on all accounts Sustainable on-call rotation