Principal full-stack engineer

Fin Opsly is the AI brain behind cost decisions across cloud, data, and AI — built to think, plan, and act. Purpose-built for today’s complex enterprise environments, we unify Fin Ops across AWS, Azure, Snowflake, Databricks, and modern AI workloads — enabling organizations to move from cost reporting to cost action. Role Summary We are seeking a Principal Full-Stack Engineer to lead the re-architecture of our PHP-based Saa S application into a modern, scalable, and robust Next.js/Node.js platform. This role blends the depth of an architect with the execution ability of a senior engineer. You will set the technical direction, design the new architecture, and also be an active contributor—writing code, reviewing code, and driving implementation. This is not a pure design role. You will be expected to lead by doing, ensuring scalability, performance, and reliability while guiding a small team to deliver at startup velocity. What You’ll do: Analyze the current PHP application and identify scalability, performance, and reliability gaps. Design a Next.js/Node.js-based Saa S architecture that supports multi-tenancy, scale, and high availability. Define and enforce best practices for modular, secure, and maintainable full-stack development. Establish standards for APIs, services, and system interoperability. Actively contribute to the codebase, building core modules and reviewing critical code. Optimize front-end rendering (Next.js SSR/SSG) and backend APIs (Node.js/Type Script) for efficiency and performance. Implement scalable service and data interaction patterns for high-throughput Saa S workloads. Collaborate with Data Engineering and Dev Ops to establish CI/CD pipelines, automated testing, monitoring, and deployments. Ensure iterative delivery while laying the foundation for long-term scalability. Leadership & Delivery Lead a small team of engineers through design, migration, and delivery. Mentor and guide the team on modern full-stack development practices. Partner with product and stakeholders to align technical architecture with business goals. Ensure iterative delivery of improvements while building for long-term scalability. What You’ll Bring 8+ years of full-stack engineering experience, with 5+ years in Saa S development. Proven expertise in Next.js (SSR, SSG, API routes) and Node.js (Express/Nest JS or similar). Strong backend architecture skills with a deep understanding of scalable service and data design. Experience with multi-tenant Saa S architectures and performance optimization. Proficiency in Type Script, REST/Graph QL APIs, and modern state management. Hands-on experience with AWS, Azure, or GCP. Strong debugging and optimization experience across frontend, backend, and data layers. Ability to set technical direction at a principal level while actively delivering code. Preferred: Experience migrating legacy systems to modern stacks. Familiarity with microservices, event-driven, or serverless architectures. Exposure to infra-as-code (Terraform, Helm) and CI/CD automation. Experience with compliance-driven Saa S (SOC2, GDPR, HIPAA). Success Criteria Current system gaps in scalability, performance, and reliability are analyzed and documented, with a clear migration plan defined. A modern Next.js/Node.js Saa S architecture is designed and implemented, supporting multi-tenancy, scale, and high availability. Production-ready features are delivered in the new architecture, showing measurable improvements in performance and efficiency. Standards and best practices for full-stack development, APIs, and interoperability are established and adopted. CI/CD pipelines, automated testing, and monitoring are in place to support reliable delivery. The engineering team is aligned to repeatable patterns for scalability and reliability.