Senior Full-Stack Engineer Nodejs React

Our client builds post-quantum cryptography solutions that help enterprises assess and manage cryptographic risk. Their flagship platform inventories cryptographic assets (certificates, keys, algorithms) across enterprise infrastructure and analyzes vulnerabilities against post-quantum threats. The platform serves the government, finance, and utilities sectors where cryptographic security is critical. We are looking for a Senior Full-Stack Engineer to join a migration project transforming the platform from single-tenant deployments to a multi-tenant, multi-cloud architecture. You’ll work on both React frontend and Node.js backend, implementing tenant isolation, hierarchical access control, and cloud-agnostic deployment patterns. This role requires in-depth backend expertise with a secondary front-end skill, focusing on containerized microservices, database architecture, and complex data migrations. You’ll collaborate with a solutions architect, DevOps engineer, QA team, and the client’s development team to deliver a proof-of-concept by January 2026, followed by production migration over the remaining contract period. The project starts with discovery and architecture design in early December 2025, with hands-on development ramping up through the 6-month engagement. Technical Details: Frontend : React (JavaScript), Nginx Backend : Node.js, Express, JavaScript Database : PostgreSQL (relational data, users, scoring rules), Elasticsearch (cryptographic facts, analytics) Infrastructure : Docker (containerization), Docker Compose (local dev only), AWS EC2 (current single-tenant), ECS/Fargate (production deployment, DevOps-managed), multi-cloud target architecture Services : SSLyze (network probe), Bootstrap CA (internal PKI), SSL/TLS throughout Testing : Zeuz (integration tests), unit testing framework (TBD during restoration) CI/CD : GitHub (existing), deployment automation (TBD) Tech Lead, 2 Software Engineers, QA Engineers, DevOps Engineer, Delivery Manager Work on platformizing a post-quantum cryptography product for scalable deployment (no cryptography expertise required — our focus is on multi-tenant architecture and deployment automation) Solve complex technical challenges: tenant-aware data segregation, multi-cloud portability, zero-downtime migrations Collaborate directly with client CTO and lead developer on high-impact architectural decisions Implement tenant isolation models for Elasticsearch (cryptographic facts) and PostgreSQL (users, scoring rules, metadata), design component-level solutions for tenant-aware queries and data segregation, and develop tenant ID propagation across all services. Build React frontend features for partner–customer–user hierarchy management, implement Node.js backend APIs for multi-tenant CRUD operations, and develop tenant-scoped analytics and reporting interfaces. Integrate OIDC/SSO authentication, implement role-based access control (RBAC) for hierarchical tenancy (partners → customers → users), and build admin interfaces for user and access management. Data migration and transformation: Plan and execute migration from single-tenant to multi-tenant data models, implement zero-downtime migration strategies with rollback capabilities, and build data validation and integrity checks. Backend API development: Extend Node.js/Express REST APIs for tenant-aware operations and optimize query performance for multi-tenant Elasticsearch and PostgreSQL. Work with Docker to containerize services (backend, frontend, Postgres, Elasticsearch, SSLyze network probe), contribute to multi-cloud deployment architecture discussions, and ensure applications are deployment-ready for container orchestration platforms. ‍ Implement multi-tenant data isolation patterns in Elasticsearch and PostgreSQL, including tenant namespace conventions and data segregation across all service layers Build React frontend components for hierarchical tenant management (partners, customers, users) and tenant-scoped dashboards Develop Node.js backend APIs with tenant-aware routing, query filtering, and data segregation enforcement Create data migration scripts and zero-downtime migration strategies for existing single-tenant deployments with validation and rollback capabilities Implement automated testing (unit and integration) for tenant isolation and data segregation scenarios Collaborate with the solutions architect on technical decisions, migration planning, architecture documentation, and component-level design proposals Partner with a DevOps engineer on container orchestration and cloud-agnostic infrastructure, and with the QA team on test case definition for cross-tenant data leakage scenarios 5+ years of full-stack development experience with React and Node.js in production environments ~ Experience using AI-powered productivity tools (Cursor, VS Code with Copilot, or similar AI-enhanced IDEs) and LLMs for research and problem-solving (ChatGPT, Claude, etc.) ~ Strong proficiency in React and modern JavaScript (ES6+) for building complex user interfaces ~ Solid experience with Node.js and Express building REST APIs with authentication and authorization ~ Experience with data migrations, including strategy design, validation, and rollback procedures ~ Clear written and spoken English for async collaboration and documentation Nice to Have Experience with multi-cloud deployments (AWS, Azure, GCP) and cloud-agnostic architecture patterns Familiarity with TypeScript (potential future migration from JavaScript) Knowledge of test automation frameworks for integration testing (experience with Zeuz is a plus) Understanding of post-quantum cryptography or cybersecurity domains Knowledge of observability tools (logging, monitoring, error tracking, APM) Background in architecture projects involving data model migrations GitHub-based workflows and conventional commits Participation in the development of high-quality products ~ Opportunity to work remotely ~