Founding Software Engineer - Full Stack

About Mantle

We’re building an AI agent to help families support their aging parents (origin story here).

Over 40M “sandwich generation” Americans currently manage their parent’s affairs. Keeping mom/dad safe and supported is like a second job: it’s time-consuming, stressful and on top of their already busy lives. We believe that managing our parents’ affairs should feel under control, easier and lower stress.

Co-founded by serial entrepreneur partners including Ted Zagat, who sold his previous businesses to Slack (announcement here) and Google (Zagat restaurant guides).

The Role

This position is core to our product and company culture. As Founding Software Engineer, you'll architect and build our consumer-facing platform from the ground up. Your job is to create exceptional web experiences that customers love, while integrating AI agents that handle complex family tasks automatically. You'll own significant parts of our technical infrastructure, work directly with founders on product direction, and make architectural decisions that will scale with millions of users.

What You'll Build

• Consumer-facing web/mobile application: onboarding flows, user dashboards, account management, and all the core web functionality families interact with daily

• AI agent experiences that integrate seamlessly into the web product, making powerful capabilities feel intuitive and trustworthy

• Robust, scalable infrastructure on AWS supporting both traditional web features and AI workloads

• Payment flows, data visualizations, notification systems, and real-time user interfaces

• Integration layers connecting AI models, third-party services, and internal systems into cohesive user experiences

• Internal tools and admin interfaces to support operations and customer success

• Data pipelines and monitoring systems to track product performance and improve the agent over time

What We're Looking For

Required Experience

• 2-10 years building production full stack web applications with modern technologies

• Strong proficiency in React and Node.js, with demonstrated ability to architect scalable systems

• Experience deploying and maintaining applications on AWS (ECS, Lambda, RDS, S3, etc.)

• Track record of shipping consumer products end-to-end, from concept to production

Ideal Background

• Early-stage startup experience (especially as a first-10 engineer)

• Experience building consumer web applications where UX, performance, and reliability matter

• Background building features across the full product spectrum - from landing pages to complex interactive workflows

• Understanding of product development and user-centric design

• Comfortable working with AI/ML APIs and integrating LLMs into product experiences

• Nice to have, but not required: experience with FinTech

Who Thrives Here

• Builders: You love creating things from scratch and taking full ownership

• Product-minded: You think about user impact, not just technical elegance

• AI-forward: You embrace modern AI development tools (Cursor, Claude Code, etc.) to move faster and build better

• Pragmatic: You balance perfection with speed and know when to ship

• Autonomous: You thrive with minimal direction and maximum responsibility

• Mission-driven: You care about building something meaningful

What You'll Get

• Meaningful work: Build a consumer product that will improve the lives of millions of families, with real technical ownership, fast pace, and huge financial potential

• Small team impact: Work directly with founders and see immediate impact from your work

• Founding team equity: Significant ownership in a company targeting a massive market

• Shape the future: You will own all things data science; your decisions will shape our product, business and culture

• Learning & growth: Exposure to every aspect of building a startup from the ground up

• Remote Fridays: Work from home every Friday. Monday through Thursday, we build together in person in San Francisco