What are the responsibilities and job description for the Senior Platform Engineer position at Harnham?
Our client is hiring a Senior Platform Engineer to serve as a technical anchor for our platform and developer experience initiatives. You’ll lead efforts to build a cohesive internal developer platform (IDP) and “paved road” that enables engineers to ship quickly, safely, and reliably.
This role sits at the intersection of backend engineering, infrastructure, and SRE. You’ll design and evolve the systems, tooling, and standards that power all product development. From CI/CD and infrastructure to observability, security, and service design.
What you’ll do
- Own major platform initiatives end-to-end, with a focus on reliability, scalability, and developer velocity across all backend services.
- Lead technical design for platform-level changes (RFCs/design docs), driving alignment across teams and making pragmatic, long-term architectural decisions.
- Build and evolve our CI/CD and GitOps workflows, improving build times, deployment safety, and release visibility across environments.
- Design and operate cloud infrastructure using Infrastructure as Code (Terraform) across AWS, ensuring consistency, scalability, and cost efficiency.
- Own and improve our container and orchestration strategy including runtime environments, service deployment patterns, and scaling strategies.
- Drive adoption of SRE best practices, including defining and measuring SLOs, improving incident response, and contributing to a sustainable on-call culture.
- Advance our observability stack (metrics, logs, traces) to enable faster debugging and better system insight.
- Strengthen platform-level security practices, including IAM design, secrets management, and secure defaults across services and infrastructure.
- Partner with backend engineers to improve system design through domain-driven design, clear service boundaries, and well-defined API contracts.
- Continuously improve developer experience (DX) by reducing friction in local development, testing, deployment, and debugging workflows.
- Raise the engineering bar through mentorship, code reviews, and by setting standards for reliability, maintainability, and operational excellence.
Tech stack
Infrastructure: AWS, Kubernetes, Docker
CI/CD: GitHub Actions, GitOps workflows
Infrastructure as Code: Terraform
Observability: Datadog
Backend: Ruby on Rails, Node.js
Data: Postgres, MongoDB
The role is intentionally backend platform hybrid. We’re looking for someone who can go deep on infrastructure (Docker, Kubernetes, Terraform, cloud) but also partner closely with backend teams on architecture, domain boundaries, and system design. This is a good opportunity for a mid/senior person who wants to do a little bit of everything.
Salary : $160,000 - $190,000