Senior Fullstack Engineer

About SpangleAI

AI is fundamentally changing how people discover products, make decisions, and shop. We’re building the intelligence that helps retailers compete and win in this new world.

Spangle is building an AI-native platform that helps retailers understand customer demand, decide how to respond, and turn those decisions into revenue. Our technology brings together intelligence about each retailer’s products, customers, and business, and puts it to work across AI discovery, paid acquisition, onsite commerce, and emerging agentic shopping experiences.

We’ve partnered with leading brands including REVOLVE, Steve Madden, Alexander Wang, and Express, delivering measurable improvements in conversion, advertising performance, and AI-driven revenue.

Founded by experienced AI and commerce leaders, Spangle has raised $21 million and earned recognition from the National Retail Federation and Business of Fashion.

We’ve built sophisticated technology, won the trust of major retailers, and demonstrated what’s possible.

Now we’re looking for an exceptional leader to help turn that foundation into a repeatable growth engine.

The Role

We are seeking exceptional Senior Fullstack Engineers with deep expertise in client-side development to build our next-generation merchant experience platform.This role primarily focuses on: Client-side SDK development, Multi-tenant architecture, Enterprise integration frameworks and High-performance frontend systems.

You will also contribute strategically to backend systems, including data modeling, infrastructure

planning, and scalable deployment architecture.

This role is ideally based in Seattle, the Bay Area, or Austin, with flexibility for exceptional

candidates.

What you'll own:

• Client-Side Platform & SDK Development: Design and implement reusable, distributed JavaScript/CSS SDK frameworks that enable seamless merchant integration across diverse retail environments. Build scalable multi-tenant frontend architecture that supports enterprise-grade customization and performance.
• Frontend Engineering: Develop high-performance, scalable, and accessible web applications using React, Next.js, and Tailwind CSS. Implement modern rendering strategies (SSR, SSG, ISR) to ensure optimal SEO and performance.
• API & Backend Integration: Partner with backend engineers to integrate frontend logic with RESTful APIs and GraphQL services. Ensure secure, resilient communication between client-side SDKs and backend systems.
• Performance & Scalability Optimization: Drive performance improvements through code splitting, lazy loading, image optimization, caching strategies, and runtime efficiency tuning.
• Code Quality & Standards: Write clean, maintainable, and reusable code. Enforce best practices for accessibility (a11y), SEO, modular architecture, and automated testing.
• Backend & Infrastructure Support: Contribute to data modeling, database schema design, infrastructure planning, and cloud deployment (AWS/GCP). Support CI/CD processes and production monitoring.

What We're Looking For

Experience

• 5+ years of professional software development experience
• Proven experience building production-grade web applications in multi-tenant or enterprise environments
• Experience developing distributed client-side SDKs or embedded commerce tools is strongly preferred

Technical Skills

• Expert-level proficiency in JavaScript, TypeScript, and CSS
• Deep expertise in React, Next.js, and Tailwind CSS
• Proficient with the AI native coding tools such as cursor, codex and claude code
• Strong understanding of multi-tenant build systems and distributed JavaScript/CSS framework design.
• Experience with RESTful APIs and/or GraphQL integrations.
• Solid understanding of data modeling, database schema design, and backend architecture principles
• Familiarity with cloud infrastructure (AWS or GCP) and modern DevOps practices
• Strong understanding of frontend performance optimization and rendering strategies

Our Culture

• GenAI-native in how we build, sell, and operate
• High ownership, low overhead, and bias toward action
• Focus on speed, experimentation, and execution
• Deep emphasis on creating clear, demonstrable customer value
• Preference for builders and operators over hierarchy
• Strong belief in in-person collaboration

Why Spangle

• Opportunity to build foundational platform technology at a fast-growing AI startup
• Direct impact on product architecture and technical direction
• Competitive salary with uncapped commission and equity
• Benefits: Health, dental, and vision insurance, 401(k), Unlimited PTO