Senior Software Developer and Team Lead (.NET)

Advanced Secure Technologies | B Corp™; Cardiff; On-site; GBP 60,000 - 66,000; Full time

Benefits offered by this job

25 days holiday + Bank Holidays

Free gym

Secure parking

Free eyecare

PerkBox discounts

Free Private online GP

Employee Assistance Programme

Job summary

Advanced Secure Technologies in St Mellons, Cardiff, an on-site, fast-growing security software company, seeks a Senior Developer and Team Lead to drive feature delivery in .NET and mentor engineers. You will shape architecture and lead sprint activities within one of our engineering teams.

The role is office-based with 37.5-hour weeks, offering a starting salary of £60,000–£66,000 DOE and up to £5,000 annual bonus, plus a comprehensive benefits package.

Qualifications

• 7+ years' commercial experience delivering modern C# .NET solutions, including at least a year at Senior level.
• Strong commitment to clean, maintainable, testable code with unit/integration testing.
• Experience with Clean Architecture or hexagonal/oignon architectures beyond traditional designs.
• Strong problem-solving, organisation and communication skills; ability to collaborate across teams.
• Experience mentoring, guiding and supporting other developers.

Responsibilities

• Design and deliver new features and platform improvements using .NET and modern technologies.
• Shape technical direction, architecture and engineering standards of our products.
• As Team Lead, own team sprint delivery, coordinate priorities and ensure releases stay on track.
• Mentor developers through technical guidance, code reviews and best practices.

Skills

C# .NET

Senior developer

Clean Architecture

Unit/Integration testing

Mentoring

Tools

Azure DevOps

CI/CD pipelines

Docker

Kubernetes

EF Core

Job description

Senior Developer and Team Lead (.NET)

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

Starting Salary: £60,000 - £66,000 DOE + up to £5,000 annual bonus

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.

Requirements

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.
• Strong problem-solving skills, attention to detail, excellent organisation and 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.

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: .NET Blazor, EF Core, SQL, Redis, Elasticsearch, RabbitMQ, Docker, Kubernetes or Blockchain.
• Experience using AI tools to improve developer effectiveness, team productivity and the quality or speed of software delivery.

Benefits

What we offer:

• Competitive starting salary £60,000 - £66,000 (DOE) + 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

• 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.
• Technical interview: Technical questions and discussion around your approach and problem-solving, includes a practical coding exercise focused on real-world problem solving.
• 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.

If you're looking for a senior engineering role where you can influence technical direction, contribute to modernisation work, and help shape enterprise-scale products,

On Site Working:

We're an office-based team because our culture thrives on collaboration and hands-on support, especially as we grow quickly and onboard new team members. While we don't offer fully remote or fixed hybrid work, we're flexible when life happens - ad hoc home working is always an option.

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.