Senior Software Developer and Team Lead (.NET)

Advanced Secure Technologies; Cardiff; On-site; GBP 60,000 - 66,000; Full time

Benefits offered by this job

Gym membership

Secure parking

Eyecare

Fully stocked kitchen

PerkBox discounts

Private online GP

Employee Assistance Programme

Cycle-to-work scheme

25 days holiday + bank holidays

Job summary

Advanced Secure Technologies in Cardiff is seeking a Senior Software Developer and Team Lead to drive design, development and delivery of .NET solutions in a modern, event-driven SaaS architecture. You will lead a cross-functional engineering team, mentor peers, and set technical direction while delivering enterprise-scale features.

The role is on-site at St Mellons with core hours 8.30am–5pm, a competitive salary (£60k–£66k) and up to £5k annual bonus, plus extensive benefits and training

Qualifications

• Proven experience operating at a senior developer/engineer level within commercial software teams.
• 7+ years’ commercial experience delivering modern C# .NET solutions, including at least a year at Senior level.
• Strong commitment to engineering best practices, including writing clean, maintainable and testable code, with unit/integration testing.
• Experience of Clean Architecture or similar modern approaches (hexagonal/onion) beyond traditional N-tier designs.
• Clear communication skills and ability to collaborate across diverse engineering teams and the business.
• Experience mentoring and guiding other developers to grow through collaboration and knowledge sharing.
• Eligible to work in the United Kingdom.

Responsibilities

• Design and delivery of new features and platform improvements using .NET 10 and other modern technologies as a senior contributor.
• Share ideas and shape technical direction, architecture, and engineering standards.
• Lead team sprint delivery, coordinate priorities, resolve blockers and ensure releases stay on track.
• Mentor developers through technical guidance, code reviews and best-practice sharing.

Skills

C# .NET

Team Leadership

Software Architecture

Unit Testing

Integration Testing

Clean Architecture

Mentoring

UK Work Eligibility

Tools

Docker

Kubernetes

RabbitMQ

SQL

Azure DevOps

Azure

Job description

Senior Software Developer and Team Lead (.NET)
StartingSalary: £60,000 - £66,000 DOE + up to £5,000 annual bonus

Location: St Mellons, Cardiff (Office-based, 5 days a week)

Are you an accomplished senior software developer with a proven track record in .NET?

Join us at an exciting time in our journey, where you’ll help shape the future of our products as we modernise our enterprise applications with latest .NET technologies and event-driven SaaS microservice architecture to deliver enterprise-scale solutions.

At Advanced Secure Technologies, we’re a fast-growing, innovative company on a mission to protect organisations from document fraud through cutting‑edge security solutions. Based on site in St Mellons, Cardiff, we’re expanding and need another skilled senior developer to help us scale.

What you’ll do:

• Play a key role in the design and delivery of new features and platform improvements using .NET 10 and other modern technologies, contributing as a senior individual contributor within one of our collaborative engineering teams.

• Share ideas, solve complex technical problems, and help shape the future technical direction, architecture and engineering standards of our products.

• As a Team Lead, take ownership of team sprint delivery, facilitating sprint activities, coordinating priorities, resolving blockers and helping ensure releases and wider project deliverables remain on track and delivered successfully.

• Support and mentor other developers through technical guidance, collaboration, code reviews and sharing best practice, while also supporting their career development and contributing to a collaborative, high‑performing engineering culture.

What you bring:

• Proven experience operating successfully at senior developer/engineer level within commercial software teams, making strong hands‑on technical contributions as a senior individual contributor.

• 7+ years’ commercial experience delivering modern C# .NET solutions, including at least a year at Senior level.

• Strong commitment to engineering best practices, including writing clean, maintainable and testable code, with experience applying unit and integration testing standards within modern development teams.

• Experience of Clean Architecture or similar modern approaches, such as hexagonal or onion architecture, beyond traditional N-tier designs.

• Clear communication skills, with the ability to collaborate effectively across diverse engineering teams and the wider business.

• Experience mentoring, guiding and supporting other developers, helping them grow through collaboration, technical guidance and knowledge sharing.

• Eligible to work in the United Kingdom.

• Able to work on‑site and comfortable working core hours of 8.30am to 5pm Monday to Friday, with flexibility for additional time against business needs.

Bonus points for:

• Working with enterprise‑scale software, microservices, event‑driven architecture or SaaS product development.

• Experience with TDD, DDD, secure coding/OWASP practices, Azure DevOps, CI/CD pipelines and cloud platforms like Azure.

• Experience with some of the tech we use: SQL, RabbitMQ, Docker, Kubernetes or Blockchain.

What we offer:

• Competitive starting salary £60,000 - £66,000 per year.

• Annual bonus potential of up to £5,000.

• A clear career pathway through our grades and beyond with mentoring and skill development support.

• 25 days holiday + Bank Holidays.

• Training and development time, plus training budgets for courses/exams.

• Free gym, secure parking, free eyecare, and a fully stocked kitchen.

• Access to PerkBox significate retailer discounts.

• Free Private online GP.

• Employee Assistance Programme including specialist clinical support

• Cycle‑to‑work schemes.

• A fun, supportive culture in an expanding company.

Interviews

Our interview process:

1. Introductory call: A chance for us to get to know you, and for you to get to know us. We’ll cover your experience, a few competency‑based questions, and some light technical discussion.
2. Technical interview: Technical questions and discussion around your approach and problem‑solving, includes a practical coding exercise focused on real‑world problem solving.
3. Final conversation: Meet our Managing Director for an informal chat about the role, the team, your potential impact, and the growth opportunity available to you.

Location and hours: Onsite, Eastern Business Park, St Mellons, Cardiff, Wales.

Min Hours 37.5hrs per week, 8.30am to 5pm Monday to Friday, with up to one hour for lunch.

Diversity & Inclusion: Advanced Secure Technologies is an equal opportunity employer, proud of our ongoing efforts to foster diversity and inclusion. We welcome applicants from all backgrounds and process your personal data in accordance with our Privacy Notice.