Principal Software Engineer

Principal Software Engineer

Department: Tech - Software Engineering

Employment Type: Permanent - Full Time

Location: Oxford, UK

Description

Based in Oxford, you will join a highly experienced and growing Software Development team building innovative, cloud-based software that supports major decisions in the global energy transition.

Our platform is built on AWS using a microservices architecture, with back-end services implemented in TypeScript on ExpressJS and AWS Lambda, and micro frontend user interfaces built in React.

As a Principal Software Engineer, you are a senior individual contributor operating on the technical leadership track. You will shape the technical foundations of our software platform, providing architectural leadership and long-term technical direction across multiple products and teams, without line management responsibility.

A core focus of this role is ensuring there is a clear, well architected model for integration between our products and across our wider ecosystem, enabling teams to move quickly and independently while remaining aligned.

Your success will be measured by the outcomes teams achieve with the technical direction, foundations, and guardrails you create, rather than by the volume of work you personally deliver.

This role is ideal for an engineer who wants to exert influence through technical excellence, architectural stewardship, and enablement, working in close partnership with Engineering Managers and Product leadership.

Key Responsibilities

Technical strategy & architecture

• Own and evolve key elements of the software architectureacross multiple products, ensuring solutions are scalable, secure, resilient, and cost effective
• Define and steward a clear, coherent integration architecture across our products and wider ecosystem, including principles and patterns for APIs, data ownership, and identity
• Establish and maintain architectural guardrails (standards, reference architectures, decision records) that enable teams to deliver autonomously while staying aligned
• Lead technical strategy on foundational capabilities that improve scalability, security, reliability, and engineering productivity as the organisation grows
• Influence product and engineering roadmaps by identifying systemic risks, architectural bottlenecks, and high leverage technical investments
• Act as a trusted technical authority for high impact decisions, balancing short term delivery needs with long term sustainability and total cost of ownership

Delivery & quality

• Raise the bar for operational excellence by helping teams adopt proven patterns for reliability, performance, security, and observability
• Invest in reusable foundations: tooling, libraries, templates, CI/CD improvements, and reference implementations to reduce friction and make high quality delivery the default
• Engage hands on selectively and deliberately, focusing on: de risking complex areas and proving out new approaches
• Champion pragmatic approaches to technical debt, helping teams make informed trade offs while keeping long term health visible and managed
• Support teams in addressing root causes of incidents and systemic issues through learning focused reviews, automation, and durable architectural improvements

Mentorship & influence

• Mentor senior and mid level engineers to strengthen architectural thinking, technical judgment, and their ability to lead complex initiatives
• Use design reviews, technical forums, pairing, and lightweight coaching to uplift capability across teams, focusing on enabling teams to solve problems independently
• Influence through clarity and collaboration: articulate technical direction, explain trade offs, and build alignment across teams and stakeholders
• Be intentional about where you engage, prioritising work that unblocks multiple teams, creates shared platforms, or removes recurring friction, rather than owning the most "interesting" problems yourself

Skills, Knowledge and Expertise

Required attributes:

• Proven track record of designing, developing, and operating complex software systems that support business critical use cases
• Strong architectural experience, with evidence of shaping systems that scale across teams and products
• Significant experience designing and evolving APIs, integration patterns, and distributed systems
• Deep expertise in at least one core technology area, with sufficient breadth to reason effectively across a modern cloud native stack
• Exceptional technical problem solving skills, including working effectively through ambiguity
• Ability to influence technical direction across teams through credibility, communication, and sound judgment
• Strong written and verbal communication skills, able to engage engineers, product leaders, and senior stakeholders
• Clear understanding of operational requirements (availability, performance, security, monitoring) and how they shape good design

Desirable attributes:

• Experience working in a platform or ecosystem style product environment
• Experience evolving architectures in fast growing or scaling organisations
• Familiarity with data platforms, or large scale integration
• Experience influencing technical strategy without formal authority

What we offer

Some of the benefits we include are:

• Private Medical Insurance
• Dental Insurance
• Parental Support
• Salary-Exchange Pension
• Employee Assistance Programme (EAP)
• Local Oxford Discounts
• Cycle-to-work Scheme
• Flu Jabs

At AER, we are committed to offering flexibility in the way we work. Most of our roles are hybrid with a mix of in-office/home working and potentially adjustable working hours. Let's discuss what works for you and AER during the interview process.

The Company is committed to the principle that no employee or job applicant shall receive unfavourable treatment on grounds of age, disability, gender reassignment, race, religion or belief, sex, sexual orientation, marriage or civil partnership, pregnancy, and maternity.

To apply, please submit your Résumé / CV, a personal summary, your salary expectations and please inform us of your notice period.
Unfortunately, we are unable to accept applications via email, telephone, or social media platforms. To be considered for this position, please submit your application using the link provided. Applications submitted through any other channel will not be reviewed.