Staff Software Engineer - Platform

Location: fully / United Kingdom

About ENSEK

ENSEK builds the cloud-native SaaS software that’s transforming how energy retailers operate, innovate and manage at scale.

We help retailers lower operating costs, improve billing accuracy for consumers, and enhance customer experience through automation and AI-driven insight, all underpinned by modern, cloud-native architecture.

ENSEK is at an exciting inflection point as we scale at pace towards new international horizons. If you’re driven by solving complex, real-world problems and want to build modern technology that accelerates the global energy transition, you’ll feel right at home with us.

About the role

We're looking for a Staff Software Engineer to provide technical leadership within our Platform Engineering organisation.

This is a hands-on technical leadership role where you'll lead one or more engineering teams responsible for the shared capabilities that power ENSEK's products and customer experiences. These include public and partner APIs, authentication and access management, platform configuration, and customer onboarding services.

You'll combine deep technical expertise with strong engineering leadership, helping shape architecture, drive engineering excellence, and mentor those around you. Working closely with Engineering Managers, Product Managers and fellow Staff and Principal Engineers, you'll play a key role in ensuring the ENSEK platform can scale to support new customers, products and international markets.

Key responsibilities

As a Staff Software Engineer, you will:

• Lead the technical direction and architecture of your team's domain, balancing immediate delivery needs with long-term platform scalability and maintainability.
• Drive architectural decision-making through design reviews, technical proposals and Architecture Decision Records (ADRs).
• Design, build and evolve secure, scalable APIs and shared platform services used by customers, partners and internal engineering teams.
• Establish and champion authentication and authorisation patterns using industry standards such as OAuth 2.0, OpenID Connect, API Keys and mutual TLS (mTLS).
• Remain hands-on in the code, contributing to the design and delivery of critical platform capabilities.
• Support the evolution of foundational services that enable customer onboarding, configuration management and platform extensibility.
• Raise engineering standards for software quality, testing, observability, security and operational excellence.
• Partner with Site Reliability Engineering (SRE) and Developer Experience teams to improve reliability, deployment processes and developer productivity.
• Collaborate with Product Managers, Engineering Managers and Technical Authors to turn customer and business requirements into clear technical solutions.
• Mentor engineers across multiple levels, fostering a strong engineering culture built on learning, ownership and technical excellence.
• Lead by example through code reviews, technical coaching and cross-team collaboration.

Key outcomes

You'll know you're making an impact when:

• Your team has a clear and well-understood technical roadmap that aligns with ENSEK's wider platform strategy.
• Core platform capabilities such as APIs, authentication services, onboarding and configuration management are secure, reliable and easy to consume.
• Internal and external consumers can integrate with the platform through well-documented, self-service capabilities with minimal bespoke support.
• Delivery performance improves through reduced lead times, more frequent deployments and higher engineering confidence.
• Reliability metrics improve through fewer incidents, faster recovery times and improved operational visibility.
• Technical knowledge is shared effectively, reducing dependency on individuals and strengthening long-term team ownership.
• Engineers around you continue to grow through mentorship, coaching and exposure to strong engineering practices.
• The wider engineering organisation benefits from improved standards, better technical decision-making and stronger collaboration between teams.

Experience required

We're looking for an experienced engineer who enjoys solving complex technical challenges while helping others do their best work.

You'll bring:

• Significant commercial software engineering experience, including experience operating as a Senior Engineer, Technical Lead or Staff Engineer.
• A proven track record of influencing technical direction beyond a single team or product area.
• Deep expertise designing, building and operating distributed systems and APIs in production environments.
• Strong experience working with relational databases, particularly SQL Server or similar enterprise-scale database platforms.
• Strong understanding of API design principles, including RESTful APIs, OpenAPI specifications, API versioning and developer experience considerations.
• Experience implementing modern identity and access management standards, including OAuth 2.0, OpenID Connect and related authentication mechanisms.
• Hands-on experience building and operating cloud-native services on AWS.
• Strong knowledge of containers and orchestration technologies, including Docker, ECS and/or EKS.
• Experience with AWS services such as API Gateway, IAM and cloud-native security patterns.
• Strong experience with Infrastructure as Code, automated testing strategies and modern CI/CD pipelines.
• Excellent communication and stakeholder management skills, with the ability to explain technical concepts to both technical and non-technical audiences.
• A track record of mentoring engineers and raising engineering standards through technical leadership.

Nice to have

• Experience working within multi-tenant SaaS platforms.
• Experience in Energy, Utilities or other highly regulated industries.
• Familiarity with Domain-Driven Design (DDD) and event-driven architectures.
• Experience building developer platforms or internal engineering tooling.
• Exposure to platform security, identity management or customer onboarding systems at scale.

Company Benefits

• 25 days’ holiday + bank holidays
• Option to buy or sell 5 extra annual leave days per year
• Vitality Health Insurance, including private healthcare, virtual GP access, mental-health support and wellbeing perks (50% off gym memberships -Virgin Active, Nuffield, PureGym)
• Pension with 5% matched contribution
• Regular team-wide and company-wide events
• 2 volunteering days per year to give back
• Remote-first working environment with offices in London and Nottingham