senior software developer - full stack.

We are seeking an experienced Senior Software Developer - Full Stack to lead the architecture, design, implementation, and integration of event-driven digital health applications. In this role, you will modernize application workflows by replacing legacy polling mechanisms with real-time, subscription-driven event architectures using FHIR Subscription and SubscriptionTopic models. Leveraging expertise across Java, Node.js, AWS serverless technologies, React, SMART on FHIR, and NextGen Connect (Mirth), you will build resilient asynchronous pipelines, develop accessible front-end interfaces, handle complex HL7 v2 and FHIR transformations, and ensure seamless interoperability across clinical registries and health information services.

Location: Toronto, ON (Onsite as-needed basis)

Duration: 4-month contract.

Advantages
Advanced FHIR Specialization: Direct hands-on implementation of cutting-edge FHIR Subscription and SubscriptionTopic event-driven architectures.

Modern Cloud & Serverless Stack: Build scalable event pipelines using AWS Lambda, asynchronous messaging, Java, and Node.js.

Clinical UI & Interoperability: Develop modern React applications leveraging SMART on FHIR workflows alongside NextGen Connect (Mirth) HL7 integrations.

Flexible Onsite Arrangement: Collaborative onsite schedule in Toronto on an as-needed basis.

Responsibilities
Assess legacy polling-based integrations and workflows to map clinical events and triggers to FHIR SubscriptionTopic and Subscription specifications.

Define, configure, validate, and maintain SubscriptionTopic and Subscription resources, managing filters, notification Bundles, lifecycle states, delivery channels, and heartbeat notifications.

Design, build, test, and maintain production-ready Java and Node.js microservices, REST APIs, publishers, consumers, and data adapters.

Develop serverless functions using AWS Lambda and asynchronous message queues to handle event processing, payload validation, enrichment, and workflow orchestration.

Implement robust distributed processing patterns, including idempotency, retries, dead-letter queues, deduplication, event replay, and automated reconciliation.

Build, test, and optimize accessible React user interfaces that implement SMART on FHIR launch flows, OAuth 2.0 authorization, scopes, and context handling.

Configure, test, and support NextGen Connect (Mirth) integration channels to receive, transform, validate, route, and acknowledge HL7 v2 messages and map them to FHIR resources.

Implement structured logging, correlation IDs, metrics, alerts, and operational dashboards to trace event delivery across publishers, message buses, and consumers.

Maintain rigorous test suites encompassing unit, integration, contract, conformance, and end-to-end regression testing for all event-driven workflows.

Ensure all technical designs, interfaces, and code adhere strictly to privacy guidelines, secure configuration standards, and personal health information safeguards.

Qualifications
Public Sector Digital Health Experience: Mandatory, proven software development experience within a public sector or provincial digital health environment (Strictly Required).

FHIR Subscription & SubscriptionTopic: Advanced experience with FHIR Subscription and SubscriptionTopic mechanisms, including resource triggers, filter criteria, lifecycle management, notification Bundles, delivery channels, heartbeat notifications, validation, and conformance testing (Strictly Required).

Event-Driven Backend & AWS Serverless: Proven hands-on development experience implementing FHIR event workflows using Java, Node.js, AWS Lambda, and asynchronous message queues, with demonstrated mastery of idempotency, retries, dead-letter handling, deduplication, and production troubleshooting (Strictly Required).

React & SMART on FHIR: Demonstrated experience building production React applications utilizing SMART on FHIR launch and authorization flows, scopes, context handling, FHIR API integration, and accessible interface design (Strictly Required).

NextGen Connect (Mirth) & HL7 v2: Strong hands-on experience configuring NextGen Connect (Mirth) channels for HL7 v2 message transformation, validation, routing, acknowledgements, and integration with provincial digital health standards and registries (e.g., Hospital Report Manager, Provider Registry, Client Registry, eReferral) (Strictly Required).

Nice-to-Have Assets:
Hands-on experience implementing the FHIR R5 Subscription framework or the R5 backport specification.

Direct experience with AWS messaging and observability tooling (e.g., Amazon SQS, SNS, EventBridge, API Gateway, CloudWatch).

Experience authoring versioned FHIR profiles, implementation guides, and API contract tests.

Summary
If you're interested in the "Senior Software Developer - Full Stack" role based in Toronto, we encourage you to apply online at

Only qualified candidates will be contacted for the next steps. We look forward to hearing from you!

Randstad Canada is committed to fostering a workforce reflective of all peoples of Canada. As a result, we are committed to developing and implementing strategies to increase the equity, diversity and inclusion within the workplace by examining our internal policies, practices, and systems throughout the entire lifecycle of our workforce, including its recruitment, retention and advancement for all employees. In addition to our deep commitment to respecting human rights, we are dedicated to positive actions to affect change to ensure everyone has full participation in the workforce free from any barriers, systemic or otherwise, especially equity-seeking groups who are usually underrepresented in Canada's workforce, including those who identify as women or non-binary/gender non-conforming; Indigenous or Aboriginal Peoples; persons with disabilities (visible or invisible) and; members of visible minorities, racialized groups and the LGBTQ2+ community.

Randstad Canada is committed to creating and maintaining an inclusive and accessible workplace for all its candidates and employees by supporting their accessibility and accommodation needs throughout the employment lifecycle. We ask that all job applications please identify any accommodation requirements by sending an email to View email address on randstad.com to ensure their ability to fully participate in the interview process.

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