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Senior Fullstack Engineer, Product

New York, New York, United States

Sage is on a mission to improve care and quality of life for older adults, starting with those residing in senior living facilities. Falls are the leading cause of injury-related death among adults over 65. And yet, fall prevention and emergency response systems for older adults are archaic and ineffective. At Sage we've built a more modern way of understanding when older adults need help, including methods for residents to alert caregivers when in need of help, and corresponding software for caregivers to triage response. Our company mission is to create a product that our client counterparts love, and this role is a key part of that objective.

Sage is a small, tight team of ambitious, multi-disciplinary entrepreneurs. We are a software-enabled, mission-driven company, and are focused only on the problems that are central to achieving that mission. At Sage, we work hard and fast but also know that to build a truly important company, we need to treat our work as a marathon, and not a sprint. The journey matters.

About this Role

We’re looking for an experienced Full-Stack Engineer to serve as a senior IC on a new, high-impact project. While you’ll bring solid backend experience, your strength and passion will be on the frontend building scalable, performant web applications in the modern React ecosystem. You’ll take ownership of the application architecture and help define the design patterns, frameworks, and best practices that shape how we build software going forward.

This role is ideal for someone who thrives on solving complex user-facing problems, has strong opinions about frontend architecture and APIs, and wants to own the end-to-end delivery of new capabilities. You’ll be hands-on, collaborative, and deeply influential in setting technical direction while ensuring that our applications are robust, secure, supportable, and optimized for scale.

We expect candidates will typically have at least 5+ years of full-stack engineering experience, with a track record of leading complex projects at scale.

Responsibilities

  • Lead Development: Architect and implement complex frontend systems in React, while contributing to backend services as needed.
  • Define Standards: Establish design patterns, frameworks, and best practices for building scalable, maintainable web applications.
  • Own Authentication & Security: Design and integrate secure authentication/authorization flows (OAuth2, OIDC, JWT) into user-facing applications.
  • Collaborate Across Stack: Work with backend and infrastructure engineers to design and optimize APIs, data flows, and integration points.
  • Optimize for Performance: Improve rendering performance, load times, caching, and responsiveness across devices and network conditions.
  • Mentor & Guide: Provide technical leadership, code reviews, and mentorship to other engineers.
  • Shape the Future: Play a central role in defining the technical trajectory of a new, mission-critical product.

Minimum Qualifications

  • Frontend Expertise
    • Deep understanding of core React concepts (virtual DOM, componentization, component lifecycle, hooks) and advanced proficiency with building complex frontends using those concepts
    • Expertise with TypeScript and modern JavaScript (ES6+)
    • Principled approach to managing application state, knowing how to leverage local, contextual, and global state management options
    • Well-reasoned opinions on route architecture and use of routing concepts (e.g. dynamic and nested routes, route guards, programmatic navigations)
    • Experience with PWA technologies (service workers, offline caching, push notifications, responsive design).
  • Full-Stack Competency
    • Working knowledge of backend technologies (Java, Node.js, or similar).
    • Experience designing and consuming RESTful and/or GraphQL APIs.
    • Comfort with relational and/or NoSQL databases.
  • Auth & Security
    • Hands-on experience implementing OAuth2, OIDC, JWT, and related authentication/authorization patterns.
    • Understanding of secure web application practices (CSRF, XSS, CORS, etc.).
  • System Design & Scalability
    • Strong understanding of how to design applications that scale.
    • Knowledge of caching strategies, asynchronous data flows, and client-server performance tradeoffs.
  • Tooling & Infrastructure
    • Experience with build systems and bundlers (Webpack, Vite, etc.).
    • Familiarity with CI/CD pipelines and modern deployment environments.
  • Collaboration & Leadership
    • Ability to lead design reviews and technical discussions.
    • Track record of mentoring peers and setting engineering standards.
    • Strong communication skills with both technical and non-technical stakeholders.

Preferred Qualifications

  • Experience working in multi-tenant SaaS platforms.
  • Familiarity with real-time applications (WebSockets, event streams).
  • Exposure to cloud environments (AWS, GCP, or Azure).
  • Experience working within design systems and contributing to and/or maintaining component libraries

Benefits and Pay

Our headquarters are located in New York City's Union Square. We believe in cross team collaboration. We think good ideas can come from anyone, and we've designed our processes to encourage participation from all. While we take our mission seriously, we don't take ourselves too seriously. We like to host offsites, outings, and team meals where we can connect as people, not just as colleagues. We offer office lunch and a fully stocked snack bar. While we are an in office culture, we allow up to 2 remote days per week.

Our benefits package for employees includes competitive base compensation along with stock options. The expected annual salary range for this role is $175,000-210,000 USD, depending on your level of expertise, your experience, and your performance in the interview process. We also provide fully-paid health and dental insurance coverage for all of our employees, along with other health benefits including vision insurance, membership to premium primary and urgent care, and online medical health providers. We also have a take as you need time off policy, in addition to 7 paid holidays and a company wide winter break during the holidays.

EEO Statement

Sage is an equal opportunity employer that is committed to diversity and inclusion in the workplace. We prohibit discrimination and harassment of any kind based on race, color, sex, religion, sexual orientation, national origin, disability, genetic information, pregnancy, or any other protected characteristic as outlined by federal, state, or local laws.

This policy applies to all employment practices within our organization, including hiring, recruiting, promotion, termination, layoff, recall, leave of absence, compensation, benefits, training, and apprenticeship. Sage makes hiring decisions based solely on qualifications, merit, and business needs at the time.

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