Senior Software Engineer

About IRIS

IRIS Software Group is one of the UK's largest privately held software companies, trusted by 100,000+ businesses, schools and accountancy firms to keep their operations running. Our software pays 1 in 6 UK employees, supports over 12,000 schools, and is relied on by 91 of the top 100 UK accountancy firms.

We're a Great Place to Work® certified employer, recognised for our commitment to well-being, inclusion and development - and we're growing fast.

You will be involved in a variety of cutting-edge technical solutions, ranging from the latest .NET technologies using C# to various Front End Web JS Frameworks, all while contributing to our AI-powered platform evolution. You will be supported in your career growth by a highly experienced team, comprehensive learning opportunities, and a vibrant technical community committed to creating exceptional solutions that make a real difference in how our customers operate and succeed.

Role Purpose

As a Senior Software Engineer, you will be a technical leader within your team, responsible for delivering complex full-stack web applications, serving millions of users, driving technical excellence, and mentoring other engineers. You'll be expected to bring commercial awareness to every technical decision, understanding that the best solution is the one that delivers value to customers and the business, not just the most elegant one. You will work hands-on with cutting-edge UI frameworks, .NET Core backends, and cloud-native technologies while contributing to architectural decisions and ensuring high-quality software delivery across containerised, scalable web products.

Key Responsibilities

Technical Delivery

Design and deliver complex, scalable systems (multi-service integrations, high-traffic APIs, data processing pipelines) that anticipate edge cases, scalability issues, and long-term maintainability

Own large features or entire components across their complete lifecycle from conception to production support

Make commercially aware technical decisions by weighing engineering trade-offs in the context of business commitments, delivery timelines, and customer impact, not just technical purity

Lead technical discussions and influence architecture decisions within team systems and components, with authority over component-level technical choices and escalation path to Engineering Lead for cross-team impacts

Drive technical excellence by establishing architectural patterns, standards, and best practices that others can follow

Ensure knowledge transfer and documentation for owned systems to enable team continuity

Collaboration & Communication

Lead with AI-first practices by actively drive AI-led ways of working within the team, using tools such as Cursor, Copilot, and Claude Code as a core part of how you design, build, and ship, while bringing others along on that journey

Lead story refinement sessions with Product Owners, providing technical expertise for estimation and risk assessment

Partner with cross-functional teams (product, design, QA) to deliver comprehensive solutions that meet business objectives

Influence technology choices based on deep technical understanding and business context

Lead team Agile ceremony facilitation to drive continuous process improvements, and establish team practices that enhance delivery predictability

Proactively identify and inspire resolution of technical debt and system improvements

Quality & Standards

Champion comprehensive quality practices including TDD/BDD standards, automated testing strategies, and shift-left testing

Lead security implementation across complex features establish security practices and conduct comprehensive security reviews

Establish development tooling and practices used consistently within the team

Lead troubleshooting efforts for complex software issues and production incidents

Establish documentation standards for complex team systems and drive knowledge transfer practices across team deliverables

Growth & Development

Mentor junior and mid-level engineers actively to raise team capability and technical standards

Lead team code review standards establishment conduct complex feature reviews, and drive quality improvements across team deliverables

Drive continuous improvement and champion responsible AI adoption with team governance practices

Required Experience & Skills

Technical Skills

Frontend Development : Strong proficiency with modern UI frameworks (e.g. Angular, React, Vue.js, Blazor) including performance optimisation and component architecture OR working knowledge with focus on backend specialisation

Backend Development : Strong proficiency with .NET Core, C#, ASP.NET Core Web APIs, REST, application architectures, and distributed systems

Database Systems and Data Architecture : Strong knowledge of SQL, NoSQL and data architecture decisions.

AI-Assisted Software Engineering: Actively engaged in AI-first ways of working by showing a genuine shift in how you approach design, development, and problem-solving with AI as a core part of the workflow, not just a productivity add-on.

Experienced integrating AI tools (Cursor, Copilot, Devin, Claude Code, etc.) into engineering practices to accelerate design, development, testing and debugging, using them critically and responsibly to improve quality, productivity and decision-making.

Observability : Advanced DataDog, Application Insights or Amazon CloudWatch implementation with performance tuning and cost optimisation

Infrastructure as Code : Infrastructure as Code with either Terraform, Bicep, ARM Templates or AWS CloudFormation/CDK

CI/CD Design : Design comprehensive CI/CD architectures for team deliverables, establish deployment strategies, and optimise pipeline performance for team efficiency

Cloud Architecture : Strong proficiency in SaaS using Azure (Functions, Queue, Blob Storage, VMs, etc) or AWS (Lambda, SQS/SNS, EC2, etc.) services, infrastructure design, and performance tuning

Container Orchestration : Strong containerisation (e.g. Docker) or Kubernetes (AKS/EKS) experience with production-scale deployments

Architecture Expertise : Expertise in clean architecture principles, SOLID design patterns, and domain-driven design

Quality & Testing : Drive TDD/BDD adoption in team testing strategy and quality governance, and implement comprehensive automated testing with continuous improvement

Scalable Solutions : Experience with highly scalable solutions and internet-facing traffic levels

Performance & Scalability : Profiling and benchmarking applications.

Application Security: Confident vulnerability management, thread modelling and tracking

Production Support : Knowledge of observability and production support practices. Proficient in debugging complex issues, performance optimization, and production troubleshooting

Experience Requirements

5-7 years of professional software development experience

Proven ability in delivering complex, multi-system solutions

Experience working with highly scalable, internet-facing solutions serving millions of users

Demonstrated technical leadership through architecture decisions, technical mentoring, and cross-team collaboration

Track record of driving technical excellence, establishing standards, and influencing technology choices

Active mentoring experience with junior and mid-level engineers

Experience leading technical initiatives that span multiple sprints or quarters

Soft Skills

Commercially aware and outcome-oriented — understands that engineering decisions exist within a business context, and prioritises delivery and customer value over technical perfection

Demonstrates resilience and adaptability in the face of changing priorities or commercial commitments — able to pivot without losing quality or motivation

Strong analysis and problem-solving skills for troubleshooting technical issues

Excellent v