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Senior Application Developer Jobs in Ontario (NOW HIRING)

Flexstaf IT

Senior Web Developer

Toronto, ON · On-site

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 ...

StackandCo

Tipperary \n \n \n \n \n \n Role Overview \n \n \n \n \n \n Senior application developers will, in collaboration with a multidisciplinary delivery team, design and develop software applications based ...

Rogers Communications

Sr. Developer

Brampton, ON · On-site

Senior Developers are responsible for server-side development of next generation products and ... Provides application and user support, troubleshooting, application testing, system integration ...

Rogers Communications

Sr. Developer

Brampton, ON

Senior Developers are responsible for server-side development of next generation products and ... Provides application and user support, troubleshooting, application testing, system integration ...

Rogers Communications

Sr. Developer

Toronto, ON

Senior Developers are responsible for server-side development of next generation products and ... Provides application and user support, troubleshooting, application testing, system integration ...

FreeBalance

Senior AWS Platform Engineer

Ottawa, ON · On-site

Use CI/CD pipelines to support infrastructure as code, not as an application DevOps role * Security ... Senior-level experience designing and operating AWS infrastructure at scale * Hands-on experience ...

CIBC US

Sr. Consultant, Full Stack Developer

Toronto, ON · Hybrid

As an Technical Lead for Application Developer, you'll be leading the design and development and be ... Within a team of senior team members, you'll broaden your technical skills and help build the bank ...

CIBC

Sr. Consultant, Full Stack Developer

Toronto, ON · Hybrid

As an Technical Lead for Application Developer, you'll be leading the design and development and be ... Within a team of senior team members, you'll broaden your technical skills and help build the bank ...

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Senior Application Developer information

What is a senior application developer?

Senior Application Developers are experienced professionals who design, build, and maintain complex software applications. They lead development teams, make key architectural decisions, and ensure that software projects meet technical standards and business requirements. In addition to writing code, they often mentor junior developers, troubleshoot high-level issues, and collaborate with other departments to deliver robust solutions. Their expertise helps organizations create scalable and efficient applications tailored to business needs.

What are the key skills and qualifications needed to thrive as a senior application developer?

To thrive as a Senior Application Developer, you need advanced programming skills, a deep understanding of software development lifecycles, and typically a bachelor’s degree in computer science or related fields. Mastery of languages like Java, C#, or Python, experience with frameworks, databases, and familiarity with version control systems (such as Git) are essential, and certifications like AWS Certified Developer or Microsoft Certified: Azure Developer Associate can be advantageous. Strong problem-solving, leadership, and communication skills help you manage projects and mentor junior developers. These skills are crucial for delivering robust, scalable applications and ensuring effective collaboration within development teams.

What are some typical challenges faced by senior application developers when leading development projects?

Senior Application Developers often encounter challenges such as balancing project deadlines with code quality, managing technical debt, and integrating new technologies into existing systems. They are typically responsible for mentoring junior developers, which requires strong communication and leadership skills. Additionally, they must collaborate closely with cross-functional teams, such as QA, UX/UI designers, and product managers, to ensure that project requirements are met while maintaining scalability and performance standards.

What is the difference between Senior Application Developer vs Application Engineer?

AspectSenior Application DeveloperApplication Engineer
Required CredentialsBachelor's degree in CS or related field; 5+ years experience; programming certificationsBachelor's degree in CS or related field; 3+ years experience; technical certifications
Work EnvironmentDesigning, developing, and maintaining applications; leading projectsImplementing, testing, and supporting applications; collaborating with development teams
Employer & Industry UsageTech companies, finance, healthcare; senior roles in software developmentIT firms, manufacturing, telecom; technical support and implementation roles

While both roles involve application development, Senior Application Developers typically lead projects and have more experience, whereas Application Engineers focus on implementing and supporting applications within technical teams.

How much does a senior application developer make?

The average salary for a senior application developer typically ranges from $100,000 to $150,000 annually, depending on experience, location, and industry. Skilled developers with expertise in specific programming languages, frameworks, or certifications may earn higher compensation. Salaries can also vary based on company size and project complexity.

What are the most commonly searched types of Application Developer jobs in Ontario?

The most popular types of Application Developer jobs in Ontario are:

What cities in Ontario are hiring for Senior Application Developer jobs?

Cities in Ontario with the most Senior Application Developer job openings:

Senior Application Developer jobs near you
Infographic showing various Senior Application Developer job openings in Ontario as of August 2026, with employment types broken down into 76% Full Time, 19% Part Time, and 5% Contract. Highlights an 89% Physical, 3% Hybrid, and 8% Remote job distribution.

Senior Web Developer

Flexstaf IT

Toronto, ON • On-site

Full-time

Posted 7 days ago

Job description

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, JavaScript, 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 professional 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 (JavaScript, 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 DevOps, 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)