Principal Software Engineer

Sideways 6; Manchester; On-site; GBP 70,000 - 100,000; Full time

Job summary

A leading software company in Manchester is seeking a Principal Software Engineer responsible for developing strategic functionality and AI integrations in their core product. Candidates should have over 10 years of experience in engineering, particularly with technologies such as C#, ASP.NET, and AWS. The role involves mentoring engineers, leading architecture discussions, and ensuring high-quality code delivery. This position offers a combination of technical leadership and hands-on development, making it ideal for seasoned professionals looking to drive innovation.

Benefits

25 days annual leave

Cycle to work scheme

Access to Learning & Development platform

Life Insurance

Auto Enrolment Pensions

Healthshield

Reimburse for personal mobile usage

Free Gym membership

Free Friday lunch

Qualifications

• Experience with large-scale, distributed systems.
• Proven development across back-end and front-end environments.
• Strong competence with SQL Server and performance tuning.

Responsibilities

• Develop strategic functionality and AI integrations.
• Lead architecture discussions and mentor engineers.
• Build secure and scalable AI integration layers.

Skills

C#

ASP.NET

ReactJS

Node.js

SQL Server

AWS

AI Integration

Agile/Scrum

CI/CD

Docker

Education

10+ years of professional engineering experience

Tools

Bitbucket

TeamCity

Octopus Deploy

Jira

Confluence

Job description

Principal Software Engineer

Department: Engineering

Employment Type: Full Time

Location: Manchester, UK

Description

Interact provides enterprise-grade intranet software that connects over three million employees to leading global names like Levi's, Domino’s, Teva Pharmaceuticals, and Technicolor.

Our team of customer‑focused problem solvers are passionate about helping organizations to communicate better. We do this together by constantly working to improve every service and product we offer. With offices in Manchester, New York, Dubai, Tulsa, and Warsaw, we operate across North America, EMEA, and Australia.

Click on any of our vacancies and you’ll see one thing in common – they all begin with this message. Why? Because at Interact we treat everyone with the same respect and honesty. Whether you’re a developer fresh out of college or a seasoned salesperson, we live the motto that we uphold for our customers: our people are our most valuable assets. We are looking for a Principal Software Engineer, who will be a hands‑on engineer responsible for fast development of strategic functionality, AI integrations in the core product, shaping the architecture, driving engineering excellence, and delivering complex features across our platform used by millions of users globally.

A core part of the role is end-to‑end execution of AI integrations into our existing ecosystem, including architecture, implementation, governance, and enablement across squads.

You will combine deep technical capability with strong leadership influence—mentoring engineers, guiding technical strategy, and personally contributing high‑quality code across our stack (C#, ASP.NET, ReactJS, Node.js, SQL Server, AWS).

A little about you...

• Design, build, and ship high‑quality, production‑grade software using C#, ASP.NET, ReactJS, Node.js, SQL Server, and AWS services.
• Serve as a hands‑on architect/engineer—writing foundational code, delivering end to end features, validating technical approaches through prototypes and spikes, and leading design discussions.
• Maintain deep familiarity with our codebase and actively contribute to critical, high‑impact features and refactoring initiatives.
• Define and uphold engineering standards across squads, including SOLID, design patterns, secure coding, and observability principles.
• Evaluate technical trade‑offs, performance implications, and long‑term maintainability to steer architectural direction.

• Lead and implement AI‑powered features across Interact’s ecosystem, to fuel value creation (eg. intelligent search, summarisation, classification, recommendation systems, generative capabilities, experience augmentation, insights generation, etc.)
• Develop secure and scalable AI integration layers using modern patterns (embeddings, RAG, vector databases, prompt orchestration, evaluation frameworks).
• Build and maintain AI‑related services, APIs, and backend components—including telemetry, evaluation pipelines, and guardrails.
• Establish best practices for responsible AI, including privacy, compliance, red‑team, fallback logic, and model governance.
• Partner with Product to prioritise AI initiatives and define measurable success metrics for user experience and business impact.
• Create reusable AI components, SDKs, documentation, and guidelines for wider engineering use.

• Lead cross‑team initiatives, unblock complex technical challenges, and ensure architectural alignment across the organisation.
• Work closely with Product & Delivery Managers to refine requirements, shape roadmaps, and ensure predictable delivery.
• Break down complex problems and guide teams through execution—participating directly in coding when needed.

• Champion testing excellence: author and maintain unit tests, integration tests, and Playwright E2E tests.
• Work closely with DevOps to optimise CI/CD pipelines (TeamCity, Octopus Deploy) and improve deployment reliability.
• Conduct in‑depth code reviews, provide hands‑on pairing, and ensure code quality across multiple squads.
• Optimise performance across APIs, databases, caching, distributed systems, and front‑end rendering.

• Maintain hands‑on involvement in resolving complex production issues, running post‑mortems, and designing long‑term solutions.
• Develop secure‑by‑default features and collaborate with Security to ensure AI and platform components meet compliance requirements.
• Contribute to scalable AWS infrastructure design and cost‑efficient resource usage.

• Mentor engineers of all levels—especially Senior and Staff engineers—to elevate technical thinking and delivery quality.
• Facilitate design clinics, architecture reviews, and knowledge‑sharing sessions, including AI education and literacy.
• Contribute to hiring pipelines through technical interviews and role calibrations.

• Stay ahead of industry trends in AI, cloud, web engineering, and developer tooling.
• Initiate and lead innovation spikes, proofs‑of‑concept, technical evaluations, and platform enhancements.
• Promote continuous improvement and foster a culture of curiosity and craftsmanship.

About the role...

• 10+ years of professional engineering experience, including designing and delivering large‑scale, distributed systems.
• Proven track record of hands‑on development across back‑end (C#, ASP.NET) and front‑end (ReactJS) environments.
• Extensive experience integrating AI/LLM technologies into production environments.
• Strong competence with SQL Server, T‑SQL, performance tuning, caching (Redis), ElasticSearch/OpenSearch, and distributed systems patterns.
• Experience operating in Agile/Scrum and collaborating closely with Product, Delivery, QA, and DevOps.
• Strong Git and CI/CD experience (Bitbucket, TeamCity, Octopus Deploy).
• Real‑world experience designing secure, scalable, resilient systems on AWS.
• Expert understanding of OOP, SOLID principles, design patterns, data structures, and algorithms.
• Deep knowledge of asynchronous processing, concurrency, distributed architectures, and high‑volume transactional systems.
• Working knowledge of Docker, containerised workloads, and cloud‑native best practices.
• Understanding of modern AI integration patterns: embeddings, vectors, RAG, prompt engineering, evaluation techniques, model safety.
• Strong familiarity with Atlassian tools (Jira, Confluence).
• Hands‑on technical leader with a bias for action and ownership.
• Excellent communicator who can simplify complex systems for technical and non‑technical audiences.
• Pragmatic, user‑centric problem solver with strong attention to detail.
• Curious, innovative, and proactive in driving the organisation forward.
• Collaborative, empathetic team player who uplifts others.
• Strategic thinker who can balance immediate delivery with long‑term architecture needs.

Benefits

• 25 days annual leave (with the option to buy and sell additional days)
• Cycle to work scheme
• Access to Learning & Development platform
• Life Insurance
• Auto Enrolment Pensions
• Healthshield (Cashback on dental check‑ups and fillings, eye tests, physiotherapy, prescriptions and much more)
• Reimburse for usage of personal mobile phone
• Free Gym membership and Free Friday lunch for office based staff