Senior Software Engineer - .NET, C# & APIs

The Role

Capco is seeking a Senior Software Engineer with strong expertise in C#, .NET, ASP.NET Core, and API development to join our Technology & Engineering practice in Toronto.

In this role, you will design, develop, modernize, and maintain enterprise applications and APIs that support business-critical solutions for our clients.

We are looking for an experienced, hands-on engineer who brings strong backend development capabilities, an understanding of modern frontend frameworks, and experience delivering secure, scalable, and reliable software.

You will collaborate with cross-functional engineering teams, contribute to technical design decisions, and leverage modern development practices, including AI-assisted engineering tools, to improve software quality and delivery efficiency.

Why This Role Is Open

We are currently hiring for this role due to an existing or newly created vacancy within our organization. This position is open as part of our ongoing business needs, and we are actively reviewing applications to fill this role with a qualified candidate who can make an immediate impact.

What You’ll Do

• Design, develop, and maintain scalable backend services and enterprise applications using C#, .NET, ASP.NET Core, and SQL Server.
• Build, enhance, and integrate secure RESTful APIs, including authentication, authorization, data validation, and error handling.
• Contribute to the modernization of existing applications, including refactoring legacy code, improving performance, and enhancing system reliability.
• Apply secure coding principles and API security practices, including OAuth2, JWT, and common application security standards.
• Participate in technical design discussions, code reviews, automated testing, troubleshooting, and performance optimization.
• Support CI/CD pipelines, containerized deployments, and development workflows using tools such as Docker.
• Collaborate with engineers, product teams, and quality specialists to deliver high-quality solutions in Agile environments.
• Leverage AI-assisted development tools responsibly to support coding, testing, debugging, and documentation while maintaining security and engineering standards.
• Share technical knowledge and contribute to continuous improvements in development practices and software quality.

What We’re Looking For

• 8+ years of professional software engineering experience, with strong hands-on development expertise in C# and .NET.
• Solid experience building and maintaining applications using ASP.NET Core, Web API, and RESTful services.
• Strong understanding of backend architecture, API design, system integrations, and object-oriented programming principles.
• Experience working with SQL Server or comparable relational databases, including data access technologies such as Entity Framework Core or Dapper.
• Understanding of application security principles, including authentication, authorization, OAuth2, JWT, and secure coding practices.
• Experience working with Git, code reviews, automated testing, CI/CD pipelines, and Agile software delivery.
• Strong problem-solving and troubleshooting skills, with the ability to investigate and resolve complex technical issues.
• Ability to collaborate effectively with cross-functional teams and communicate technical concepts clearly.

Bonus Points For

• Experience modernizing legacy .NET applications or migrating enterprise systems to modern architectures.
• Exposure to Azure or AWS cloud environments, Docker, Kubernetes, or cloud deployment troubleshooting.
• Experience with performance optimization, application monitoring, and production support.
• Familiarity with accessibility standards such as WCAG or AODA.
• Experience with Snowflake, data warehouses, or enterprise data integrations.
• Experience…