We are seeking an experienced Web Services & Application Developer with strong C#, ASP.NET , and SQL Server capabilities to maintain, modernize, and enhance legacy web applications, REST services, and SOAP web services.

In this role, you will bridge the gap between web application maintenance and backend service integration, ensuring system stability, building secure APIs, and optimizing complex database workflows.

Key Responsibilities Application & API Development: Design, build, and maintain Web API services, REST Services, SOAP web services, and existing ASP.NET applications using C#, .NET Framework, HTML5, CSS3, Java

Script, and AJAX.

Service Integration & Modernization: Develop and consume RESTful APIs and SOAP/WCF web services to enable seamless integration across enterprise platforms and legacy architectures.

Backend Data Engineering: Write complex SQL queries, stored procedures, user-defined functions, triggers, and views in T-SQL, optimizing database performance and data exchange workflows.

Legacy Refactoring & Security: Identify performance bottlenecks in web applications and web services; refactor and optimize C# code and database scripts for performance, scalability, and security (e.g., OWASP compliance, SQL injection prevention).

System Support & Integration: Support system integration testing, debug web service communication, resolve production issues,



and document technical architecture and API endpoints.

Required Qualifications Experience: 5+ years of qualified software development experience with C#, ASP.NET , Web Services, and Microsoft SQL Server.

Core Tech Stack: Deep proficiency in C# , ASP.NET , REST Services (Web API) , and SOAP Services (WCF / ASMX) , alongside front-end fundamentals (Java

Script, jQuery, HTML5, CSS3).

Web Services & API Design: Strong hands-on experience designing, consuming, and securing RESTful JSON endpoints and XML-based SOAP contracts (WSDL, XSD, SOAP envelopes). T-SQL Mastery: Advanced skills in writing and optimizing complex T-SQL queries, stored procedures, execution plans, and database indexing to support service payloads.

Version Control: Experience with Git, Azure Dev

Ops, or Team Foundation Server (TFS).

Preferred Qualifications Experience migrating legacy ASP.NET applications and SOAP services to modern frameworks ( ASP.NET Core, RESTful microservices, Angular, or React).

Deep understanding of IIS server configuration, SSL/TLS certificates, and API security authentication models (OAuth 2.0, JWT, API Keys, Basic Auth).

Knowledge of cloud platforms (Azure Web Apps, Azure API Management, Azure SQL) or C# unit testing frameworks (xUnit, NUnit, Moq)

📌 Senior Web Developer (Toronto)
🏢 FlexStaf IT
📍 Toronto