Senior Software Developer
Location: Cardiff (Office-based, 5 days a week)
Salary: £57,250 - £66,275 base (DOE) + up to £3,000 annual bonus
Start Date: Early 2026
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 cutting-edge .NET technologies and event-driven SaaS microservice architecture to deliver enterprisescale 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 developer to help us scale.
What you’ll do:
• Develop and enhance our secure web applications using .NET 10.
• Apply best practices to write clean, maintainable, testable code.
• Collaborate with other talented developers, taking on complex challenges.
• Share ideas, solve problems, and help shape the future of our products.
Requirements
What you bring:
• 7+ years' commercial experience in modern C# .NET development, including
time at senior level.
• Proven ability in maintaining high testing standards (unit and integration tests).
• Some experience of Clean Architecture, or similar (hexagon/onion etc) beyond traditional N-tier designs.
• Strong problem-solving skills, attention to detail, and excellent communication.
• Ability to mentor, guide and lead other developers, influencing technical direction and best practices.
Bonus points for:
• Working with enterprise-scale software, microservices, event-driven architecture or SaaS product development.
• Experience with some of the tech we use: .NET Blazor, EF Core, SQL, Redis, Elasticsearch, RabbitMQ, Docker, Kubernetes or Blockchain.
• Experience with TDD, DDD, secure coding/OWASP practices, Azure DevOps, CI/CD pipelines and cloud platforms like Azure
Benefits
What we offer:
• Competitive salary £57,250 - £66,275 (DOE) + monthly performance bonus.
• A clear career pathway through our Senior Developer 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
• Company car and cycle-to-work schemes.
• A fun, supportive culture with birthday treats and epic office events.
Selection Process:
• Introductory call (45m): 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 assessment (90m): Technical questions and discussion around your approach and problem-solving, includes a 30-minute practical coding exercise.
• Final conversation (20m): Meet our Managing Director for an informal chat about the role, the team, and your potential impact.
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 ready to accelerate your development career, gain hands-on experience with the latest Microsoft technologies, and work towards becoming a Senior Developer, apply now – we can’t wait to see what you’ll bring!
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