Senior Cloud Applications Architect – .NET / AWS

We are seeking a Senior Cloud Applications Architect with deep C#/.NET expertise and proven experience modernizing legacy applications in AWS environments. This role is part of a large enterprise cloud modernization program supporting complex applications in the energy sector.

The successful candidate will be a hands-on architect who can bridge application architecture and implementation. You will help define and execute modernization approaches for legacy .NET workloads, working closely with application engineering, cloud, security, database and enterprise architecture teams.

This is not a purely theoretical architecture role. We are specifically looking for someone who has personally led or executed real-world legacy .NET modernization projects and can demonstrate how those applications were transformed, deployed and operated in production.

What You'll Do

• Lead and contribute to the modernization of legacy .NET applications into modern .NET and AWS-based architectures.

• Assess existing application architectures and define practical modernization strategies, including refactoring, decomposition, containerization and migration.

• Support Endur scripted and packaged installations and deployment of .NET/JVS extensions.

• Drive SQMD .NET modernization and related application architecture activities.

• Design and support containerized application workloads using AWS ECS and related AWS services.

• Modernize application integrations and event-driven workflows using services such as Amazon SQS and SNS.

• Support authentication and authorization modernization, including MEA authentication requirements.

• Define application interfaces, integration patterns, deployment approaches and technical standards.

• Collaborate with cloud/infrastructure, security, database, application engineering and enterprise architecture teams.

• Review technical designs and code-level implementation decisions, identify risks and dependencies, and provide hands-on technical guidance.

• Participate in migration planning, testing, deployment and production transition activities.

• Communicate architecture decisions, trade-offs and technical risks clearly to client and internal stakeholders.

What We're Looking For

• Strong hands-on experience with C# and .NET, including both legacy .NET Framework and modern .NET/.NET Core.

• Demonstrated experience leading or executing legacy .NET application modernization projects in real production environments.

• Strong AWS application architecture experience, with the ability to design and implement application workloads rather than focusing only on infrastructure.

• Experience with containerized .NET applications and AWS ECS or a comparable container platform.

• Experience with APIs, distributed systems, application integration and event-driven architecture.

• Practical experience with messaging technologies such as Amazon SQS and SNS.

• Strong understanding of application security, authentication/authorization, encryption in transit and at rest, and secure cloud application design.

• Ability to explain and defend architectural decisions, technical trade-offs and modernization approaches.

• Comfort working hands-on with engineering teams while operating at an architecture level.

• Strong English communication skills and the ability to work effectively with US-based technical stakeholders.

Preferred Qualifications

• Experience with Endur and/or JVS.

• Experience in energy, commodities, trading, financial services or another complex enterprise environment.

• Experience with AWS services such as ECS, EC2, ECR, SQS, SNS, RDS, API Gateway, IAM, S3, Lambda or Secrets Manager.

• Experience with CI/CD and cloud-native engineering practices.

• AWS certification(s).

• Experience working across distributed or US-based engineering and architecture teams.

What Success Looks Like

• You can take a legacy .NET application and explain a credible path from its current state to a modern, supportable AWS architecture.

• You have personally delivered or led modernization work rather than only creating high-level roadmaps.

• You can work comfortably across architecture, application engineering and cloud teams.

• You can make practical decisions around containerization, integration, messaging, security and deployment.

• You can communicate technical decisions clearly with senior engineers, architects and client stakeholders.

Important Note for Candidates

The client will place significant emphasis on demonstrated hands-on C#/.NET expertise and real-world modernization experience. Candidates should be prepared to discuss a specific legacy .NET application they have modernized, including their role, the starting architecture, the target architecture, key technical decisions, AWS services used, challenges encountered and the production outcome.