Senior Software Engineer - NWX Networx

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.

The Opportunity

Join a team at the heart of a major technology transformation. We're evolving a market-leading Applicant Tracking System from a legacy monolithic platform into a modern, cloud-native Azure application, and we're looking for a Senior Software Engineer who wants to do more than just write code. This is an opportunity to influence architecture, mentor developers, champion engineering best practices, and help shape the future direction of a product used by thousands of customers.

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 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
• 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 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 ASP.NET MVC, including performance optimisation and component architecture OR working knowledge with focus on backend specialisation
• Backend Development : Strong proficiency with .NET Core, C#/VB.NET , ASP.NET Core Web APIs, REST, application architectures, and distributed systems
• Database Systems and Data Architecture : Strong knowledge of SQL, NoSQL, CosmoDB and data architecture decisions.
• AI-Assisted Software Engineering : Experience with integrating AI tools (Cursor, Copilot, Devin, Claude Code, etc.) in 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 Requirments

• 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

• Strong analysis and problem-solving skills for troubleshooting technical issues
• Excellent verbal and written communication skills with ability to explain technical concepts to non-technical stakeholders
• Technical leadership and influencing skills without formal authority
• Ability to utilise technical skills to develop and coach others through mentoring and knowledge sharing
• Collaborative approach and ability to work as part of wider Engineering and QA teams
• Conflict resolution skills for technical disagreements and cross-team coordination
• Learning mindset with ability to adapt to new industry trends

Desirable Skills

• Experience working with regulated or complex domains (finance, health, govtech) with audit requirements
• Experience designing high-quality AI interactions through effective prompt engineering, efficient token usage, and optimisation techniques, combined with practical use of the Model Context Protocol (MCP) to integrate AI systems with tools and services for richer, automated workflows
• Expertise with advanced monitoring and APM strategies using DataDog, including custom dashboards and alerting
• Expertise with modern UI architecture patterns (micro-frontends, SSR/SSG)
• Knowledge of security best practices and compliance requirements (OAuth2, OIDC, RBAC)

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