Senior Software Developer

4 days ago Be among the first 25 applicants

Get AI-powered advice on this job and more exclusive features.

This range is provided by Advanced Secure Technologies. Your actual pay will be based on your skills and experience — talk with your recruiter to learn more.

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

Job Overview: 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 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 developer to help us scale.

• 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

• 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

• 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, Rabbit
  
  MQ, Docker, Kubernetes or Blockchain
• Experience with TDD, DDD, secure coding/OWASP practices, Azure Dev Ops, CI/CD pipelines and cloud platforms like Azure

• 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 Perk Box significant 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

• 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

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!

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.

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.