Principal Full Stack Engineer

Our client is seeking a Principal Full Stack Engineer on a contract basis to provide technical leadership and hands-on engineering across the design and delivery of scalable APIs, modern web applications, and cloud-native platforms. This is a senior technical leadership role for an engineer who can operate at both the architecture and implementation level—setting technical direction, making key design decisions, establishing engineering standards, and solving complex technical challenges while remaining actively involved in development. Duration: 12 months Location: 4d/week hybrid Markham Responsibilities Provide hands-on technical leadership and architectural direction for complex, enterprise-scale applications and platforms.Define solution architecture, engineering patterns, technical standards, and development best practices across the application landscape.Design and build highly scalable APIs and full-stack applications using React, NestJS/Node.js, Spring Boot, and modern cloud technologies.Lead the design of event-driven architectures, microservices, integration patterns, and distributed systems.Evaluate architectural options, identify technical trade-offs, and provide clear recommendations to engineering and business stakeholders.Drive cloud-native architecture and deployment using Azure Container Apps, Azure API Management (APIM), Docker, and related Azure services.Establish and improve CI/CD practices using Azure DevOps, including branching strategies, automated deployments, release management, and production controls.Define and implement Infrastructure as Code using Bicep, Terraform, ARM Templates, Pulumi, or similar technologies.Provide technical direction for relational and NoSQL database architecture, performance, scalability, and integration.Lead complex technical design reviews and provide guidance to senior engineers and development teams.Establish engineering standards for scalability, security, reliability, maintainability, observability, and performance.Define observability strategies using Azure monitoring, logging, distributed tracing, telemetry, dashboards, and alerting.Drive modern deployment practices including feature flags, incremental releases, automated testing, and progressive delivery.Lead planning for production deployments, complex releases, technical migrations, and remediation initiatives.Troubleshoot and lead resolution of complex architectural, performance, integration, and production issues.Identify technical debt and establish pragmatic strategies for modernization and continuous improvement.Mentor engineers, elevate engineering practices, and provide technical guidance across multiple teams and initiatives.Partner with product, architecture, security, infrastructure, and business stakeholders to translate business requirements into scalable technical solutions.Maintain strong ownership of technical outcomes while balancing delivery timelines, engineering quality, risk, and evolving business priorities. Requirements 12+ years of software engineering experience, with extensive experience designing and building scalable APIs, distributed applications, and enterprise platforms.10+ years of modern web application development experience, including strong hands-on expertise with React and Node.js frameworks; NestJS strongly preferred.Proven experience operating as a Principal Engineer, Lead Engineer, Staff Engineer, Architect, or equivalent technical leadership role.Strong hands-on experience designing and developing scalable Spring Boot APIs.Deep expertise in event-driven architecture, microservices, distributed systems, API design, and enterprise integration patterns.Demonstrated experience defining application architecture and making technical decisions across complex, large-scale systems.Hands-on experience with Azure Container Apps, Azure API Management (APIM), Docker, Azure DevOps CI/CD, and related cloud-native technologies; comparable AWS experience may be considered.Strong Infrastructure as Code experience using Bicep, Terraform, ARM Templates, Pulumi, or equivalent technologies.Strong knowledge of SQL and NoSQL database technologies, including data modelling, scalability, and performance considerations.Experience defining and managing branching strategies, code merges, release processes, deployment strategies, and production releases.Strong understanding of application security, resiliency, scalability, observability, performance, and production-readiness principles.Proven ability to evaluate multiple solution approaches, articulate technical trade-offs, and drive architectural decisions.Ability to communicate complex technical concepts to engineers, architects, product leaders, and senior business stakeholders.Demonstrated ability to mentor and influence senior engineers without relying on direct management authority.Strong analytical and problem-solving skills with experience leading resolution of complex technical and production issues.Strong ownership mindset with a track record of delivering production-ready solutions in complex enterprise environments.Ability to balance architectural excellence with pragmatic, incremental delivery and changing business requirements. Nice to Have Experience designing or developing discounting, pricing, promotions, or rules engines.Experience with TanStack within React applications.Experience producing architecture diagrams, technical design documents, ADRs, and solution-option analyses.Experience with Application Insights, Log Analytics, distributed tracing, dashboards, alerting, and telemetry-driven troubleshooting.Experience with Agile delivery tools including Azure DevOps (ADO) and JIRA.Experience leading modernization, technical debt remediation, platform transformation, or large-scale application migration initiatives.Experience establishing engineering standards and development practices across multiple teams.Experience with secure AI-assisted software development tools and associated security and governance considerations.Strong technical leadership, planning, organization, communication, and presentation skills.Demonstrated ability to balance speed of delivery, engineering excellence, architectural trade-offs, risk, and competing priorities.