At CGI, you’ll play a pivotal role in building and sustaining secure, high-impact applications that underpin critical services for our clients. As a C# Developer, you’ll contribute to the full application lifecycle, combining hands-on development with 4th line support to ensure resilient, high-performing systems. Working within a collaborative, ownership-driven culture, you’ll help deliver measurable outcomes, strengthen long-term client relationships, and shape solutions that make a real difference in a highly secure environment.
CGI was recognised in the Sunday Times Best Places to Work List 2025 and has been named a UK ‘Best Employer’ by the Financial Times. We offer a competitive salary, excellent pension, private healthcare, plus a share scheme (3.5% + 3.5% matching) which makes you a CGI Partner not just an employee. We are committed to inclusivity, building a genuinely diverse community of tech talent and inspiring everyone to pursue careers in our sector, including our Armed Forces, and are proud to hold a Gold Award in recognition of our support of the Armed Forces Corporate Covenant. Join us and you’ll be part of an open, friendly community of experts. We’ll train and support you in taking your career wherever you want it to go.
Due to the secure nature of the programme, you will need to hold UK Security Clearance or be eligible to go through this clearance. This is a full-time onsite position based in our Reading office, five days per week. UK sole nationality is required.
Your future duties and responsibilities
In this role, you will develop, maintain, and support a secure application using C#, ASP.NET, and SQL Server, taking ownership of both new functionality and the stability of a mature system. You’ll work closely with colleagues and, where appropriate, directly with the client, building trust through clear technical communication and reliable delivery. Supported by experienced peers, you’ll grow into a trusted technical authority and subject matter expert for the customer environment.
You will contribute to continuous improvement by applying strong software development practices, diagnosing complex issues, and ensuring solutions meet the highest security and quality standards.
Key responsibilities include:
- Develop & enhance secure applications using C# and ASP.NET
- Support & resolve complex 4th line application issues
- Analyse, debug, and improve mature production systems
- Manage code and work items using Azure DevOps
- Collaborate with stakeholders and communicate technical solutions clearly
- Contribute to best practice within a highly secure delivery environment
Required qualifications to be successful in this role
You will bring solid experience in Microsoft-based application development, with the ability to support and enhance secure, business-critical systems. You should be comfortable working with established codebases, applying strong debugging skills, and communicating effectively with both technical and non-technical stakeholders.
Essential qualifications:
- Strong experience with C# and ASP.NET
- Proven experience using SQL Server
- Familiarity with the Microsoft development toolchain
- Good understanding of modern software development practices
- Experience supporting and debugging mature applications
- Ability to work effectively in a secure environment
- Clear and confident technical communication skills
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Together, as owners, let’s turn meaningful insights into action.
Life at CGI is rooted in ownership, teamwork, respect and belonging. Here, you’ll reach your full potential because…
You are invited to be an owner from day 1 as we work together to bring our Dream to life. That’s why we call ourselves CGI Partners rather than employees. We benefit from our collective success and actively shape our company’s strategy and direction.
Your work creates value. You’ll develop innovative solutions and build relationships with teammates and clients while accessing global capabilities to scale your ideas, embrace new opportunities, and benefit from expansive industry and technology expertise.
You’ll shape your career by joining a company built to grow and last. You’ll be supported by leaders who care about your health and well-being and provide you with opportunities to deepen your skills and broaden your horizons.
Come join our team—one of the largest IT and business consulting services firms in the world.
