Senior Full Stack Application Developer

Title: Senior Full Stack Application Developer

Salary: $110,000 - $130,000 + Benefits + Vacation (exact placement within this range will depend on skills and qualifications)
Location:  Thornhill, Ontario (hybrid) 
Length: Full-time, permanent 

About Us: 

At WellnessLiving, we empower thousands of health and wellness business owners to turn their entrepreneurial dreams into reality. Our mission-critical software fuels their vision, supporting millions of clients around the world in their wellness journeys. With a deep commitment to putting our customers first, we foster a culture that values high performance, adaptability, and accountability. If you are a skilled professional who thrives in a fast-paced, customer-focused environment and are passionate about making a meaningful impact on the health and wellness industry, we would love to connect with you.    
 
Our team is driven by four core values that shape everything we do. If you share these values and meet the qualifications outlined for this role, we encourage you to apply - we’d love to learn more about you!   

Customer First – We approach every challenge with a customer-focused lens, driven by an obsession with our customers’ happiness and success.    

Excellence – We approach every task, whether big or small, with a steadfast commitment to exceptional execution and the pursuit of greatness.    

Accountability – We take full ownership of our decisions, actions, and outcomes – both successes and failures.    

Adaptability – We recognize that sustained success demands that we be malleable and purposefully evolve, acknowledging that the world is dynamic and constantly changing. 

About the Role:

We are seeking a Senior Full-Stack Application Developer to play a key, hands-on role in our microservices and domain-driven modernization journey. This role is ideal for an experienced engineer who combines strong frontend craftsmanship with backend and distributed systems thinking and has implemented (not just discussed) modern cloud-native architectures. 

You will design, build, and evolve scalable, event-driven, multi-tenant SaaS applications used across multiple brands in the healthcare and fitness technology space. You will work end-to-end, from React-based user experiences to secure APIs and microservices built with Node.js and Java (Spring Boot) while collaborating closely with product, architecture, DevOps, and data teams. 

This role requires direct implementation experience, an ownership mindset, and the ability to work effectively in an environment where systems are actively transitioning from monolithic patterns to domain-aligned microservices. 

Key Responsibilities:

Full-Stack Application Development 

• Design, develop, and maintain production-grade full-stack applications using React, Node.js, and Java/Spring Boot 
• Build modular, reusable frontend components aligned with design systems, accessibility standards, and responsive UX best practices 
• Develop secure, scalable RESTful and event-driven APIs, ensuring performance, reliability, and backward compatibility 

Microservices, DDD & Event-Driven Systems 

• Implement microservices aligned to business domains and bounded contexts 
• Contribute to domain-driven design (DDD) discussions and translate domain models into working services 
• Design and implement event-driven workflows using messaging or streaming platforms (e.g., Kafka, Kinesis, SNS/SQS) 
• Apply patterns such as idempotency, event versioning, and eventual consistency 
• Implement and integrate modern authentication and authorization solutions using OAuth2, OpenID Connect (OIDC), and JWT 
• Work hands-on with identity platforms such as Auth0 and/or FusionAuth 
• Design role-based and permission-based access controls suitable for multi-tenant SaaS environments 
• Build and deploy services using Docker, Kubernetes, and AWS 
• Own services throughout their lifecycle: CI/CD, deployment, monitoring, and production support 
• Use infrastructure-as-code and automated pipelines (e.g., GitHub Actions, Terraform/CloudFormation) 
• Implement logging, monitoring, and alerting using tools such as Datadog, ELK, or Splunk 
• Write clean, testable, and maintainable code with appropriate unit, integration, and contract testing 
• Participate in code reviews, architecture reviews, and technical decision-making 
• Collaborate cross-functionally with Product, UX, QA, and Platform teams in an Agile environment 
• Mentor junior engineers and help raise overall engineering standards 

AI-Augmented Development 

• Leverage AI-assisted development tools (e.g., Copilot, ChatGPT, internal AI tools) to improve productivity, code quality, and learning 
• Apply engineering judgment to validate, refactor, and test AI-assisted outputs 
• Use AI responsibly for tasks such as scaffolding, refactoring, test generation, and documentation, and not as a substitute for engineering fundamentals 

Required Qualifications & Experience 

• Bachelor’s degree in computer science, Engineering, or equivalent practical experience 
• 5+ years of hands-on full-stack development experience in production environments 
• Strong experience with React, including Hooks, Context, and component-driven architecture 
• Proficiency in JavaScript/TypeScript, HTML5, CSS3/SASS, and modern frontend tooling 
• Hands-on experience building API-first microservices using Java (Spring Boot), Node.js, and/or Python (FastAPI), with a strong emphasis on contract-first design (OpenAPI), backward compatibility, and service evolution 
• Practical experience with microservices architectures, including service decomposition and inter-service communication 
• Strong understanding of REST, OAuth2, OIDC, JWT, and API gateway patterns 
• Experience with Docker and Kubernetes in real production systems 
• Experience with cloud platforms (AWS preferred) and CI/CD pipelines 
• Working knowledge of relational and NoSQL data stores (e.g., MySQL, Redis, MongoDB, DynamoDB) 
• Experience with monitoring, logging, and observability in distributed systems 
• Comfortable working in Agile teams (Scrum/Kanban) 

Nice to Have 

• Experience with Event Streaming / Messaging platforms (Kafka, Kinesis, SNS/SQS) 
• Exposure to Micro Frontend architectures (Module Federation, single-spa) 
• Experience with multi-tenant and white-label SaaS platforms 
• Familiarity with PHP-based legacy systems and modernization efforts 
• Knowledge of accessibility (WCAG) and internationalization 
• Experience in healthcare, fitness, or regulated SaaS environments 

Please note that only those selected for an interview will be contacted.   

We appreciate you taking the time and look forward to reviewing your application! 

WellnessLiving is proud to be an equal opportunity employer. We base employment decisions solely on qualifications, experience, and business needs. We do not tolerate discrimination or harassment of any kind. All qualified applicants will receive consideration without regard to race, color, religion, creed, gender, gender identity or expression, sexual orientation, national origin, disability, age, genetic information, veteran status, marital or family status, or any other status protected by applicable laws. 

We utilize AI to generate summaries of interview notes as part of our candidate evaluation process. This helps ensure a fair and consistent review while maintaining a human-centered hiring approach.