Senior Full Stack Engineer (Product) - AI Workflow / Application Builder (Sonoma)

🚀 Senior Full-Stack Engineer High-Growth AI SaaS Startup

📍 SoMa, San Francisco, CA | 💼 Full-Time | Onsite

💰 Salary : $200K$325K + Meaningful Equity (1%+)

Join an early-stage AI SaaS startup building an application builder that empowers business users to create custom applications where humans and AI collaborate seamlessly across enterprise workflows. Youll play a pivotal role in shaping core architecture, product development, and first production deployments , working directly with the founder and early team.

About the Role

Were seeking a Senior Full-Stack Engineer to lead product development and own major product surfaces across frontend, backend, and integration layers . This is a high-impact role where youll directly influence product direction and help build the foundation for Lumenas platform.

What Youll Do

• Design and build the core application builder the orchestration layer connecting workflows, agents, and front-end views.
• Develop and scale Lumenas TypeScript-based backend and modern frontend stack ( React + Tailwind ).
• Build dynamic frontend interfaces for dashboards, forms, and human-AI workflows.
• Collaborate with the applied engineering team to integrate automation and intelligence across systems.
• Shape and maintain the integration layer connecting REST APIs, SQL sources, and third-party systems.
• Define and enforce best practices for product engineering, architecture, and developer experience as the company scales.

Who You Are (Must-Haves)

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