Fullstack Sr Software Dev Engineer

Yahoo serves as a trusted guide for hundreds of millions of people globally, helping them achieve their goals online through our portfolio of iconic products. For advertisers, Yahoo Advertising offers omnichannel solutions and powerful data to engage with our brands and deliver results. About The Team Membership platforms at Yahoo provide modern, secure identity offerings for consumers and businesses interacting with Yahoo systems. These platforms operate at massive scale, serving hundreds of millions of users every day, and power critical authentication, authorization, account management, privacy, wallet and loyalty capabilities across Yahoo products that leverage an AI-assisted support experience and a world-class, cost-effective Yahoo Global Customer Care team. As part of Yahoo's transition to an AI-First engineering model, teams increasingly leverage AI-assisted development environments combined with Spec-Driven Development (SDD) workflows, to accelerate delivery while maintaining high engineering quality. About The Role We are looking for a Senior Full Stack Software Dev Engineer who is ready to build the next generation of secure, scalable Customer Care systems that serve hundreds of millions of users globally. As a Senior Professional, you possess specialized depth in full-stack architecture and a commitment to modern, AI-augmented engineering practices. In this role, you will work independently with guidance only in complex situations, owning critical features and acting as a technical resource for your peers. A core expectation of this role is the ability to collaborate effectively with generative AI systems—using structured specs, deep codebase context, and prompt modeling to guide high-quality software implementation. We seek engineers who possess an experimentation-forward mindset and view AI as a force multiplier for architectural excellence and team-wide productivity. Responsibilities • Design, build, and operate high-scale Customer Care and Identity systems using React, TypeScript, and Java/Node.js with a strong focus on security and availability. • Lead an AI-first development workflow within the squad, utilizing precise markdown specifications to drive AI-assisted code generation (such as Cursor and Claude Code), while taking ownership of the validation, testing, and safety of all generated assets. • Own complex full-stack features end-to-end, from initial technical requirements and system design to production monitoring and operational excellence. • Proactively identify and implement AI-driven efficiencies in your daily engineering workflows, replacing repetitive manual tasks with structured automation, custom templates, and AI-assisted testing. • Optimize system performance and reliability by diagnosing systemic bottlenecks and proactively implementing AI-assisted performance profiling and diagnostics. • Mentor engineers across the squad, raising engineering standards through peer reviews, detailed design sessions, and scaling modern AI-first development best practices. • Exercise critical technical judgment to audit, validate, and debug AI-generated code outputs, ensuring all implementations meet Yahoo's rigorous security and performance standards. • Collaborate cross-functionally with Product Managers, UX Designers, Security Engineers, and adjacent Yahoo product squads to coordinate complex technical integrations. Basic Qualifications • Bachelor's degree in Computer Science, a related technical field, or equivalent practical experience. • 5–8 years of professional full-stack software engineering experience. • Strong hands-on engineering experience using Java for robust, secure backend services. • Experience building responsive, high-performance web applications using React.js, Node.js, JavaScript/TypeScript, and modern frameworks (e.g., Next.js). • Strong fundamentals in system design, RESTful APIs, distributed systems, and web security protocols. • Proven expertise in prompt engineering, context modeling, and structured interaction with AI development environments to build and refactor production-grade systems. • Demonstrated experience integrating AI-assisted developer tools (e.g., Cursor, Claude Code, GitHub Copilot) into day-to-day software development workflows. • Proven capability to critically evaluate, audit, and debug AI-generated outputs, ensuring the detection of errors, hallucinations, or security vulnerabilities. • Deep experience with testing frameworks, modern CI/CD pipelines, and maintaining high codebase standards. Preferred Qualifications • Experience building or maintaining high-scale Identity and Access Management (IAM) systems, auth protocols (OAuth, OIDC, SAML), or web security standards. • Experience with CRM and CMS tool integrations. • Cloud platform experience (GCP, AWS) and infrastructure-as-code. • Familiarity with observability tools (Splunk, Grafana, DataDog) and client/server performance profiling. • Experience with structured development metho