Senior Full Stack Engineer

Avantos • Saint Louis, MO

4d • Remote

About The Position

Avantos is building the industry’s first AI-native operating system for financial services , redefining how firms onboard clients, deliver advice, and manage core servicing workflows. Our platform unifies fragmented data, automates complex processes, and embeds intelligent decision-making across every step of the client lifecycle. We partner with leading financial institutions and are scaling rapidly. We’re an execution-driven, design-obsessed, product-led team composed of founders and leaders from Wharton, MIT, top design programs, and prior unicorn SaaS companies. We move fast, solve deep industry problems, and build technology that puts users back in control of their workflows. If you love client impact , product design , complex problem solving , and bringing AI-enabled change to real-world businesses , Avantos is where you will thrive. We’re looking for a Senior Full Stack Engineer with a strong frontend core — someone who thinks in React/Next.js first , but is fully capable of contributing at the backend layer using Golang when needed. Lead frontend architecture and experience design — owning React/Next.js interfaces end-to-end, with a focus on performance, UX, and scalability. Integrate cleanly with backend services and contribute to Golang APIs when needed — not just consume them. Collaborate tightly with product and design on experience decisions — not just implementation . Influence architecture, reliability, performance strategy, and engineering standards . Write high-quality, clean, well-structured code — and enforce that quality in reviews. Act as a technical force multiplier — mentoring, unblocking, and setting the technical bar.

Requirements

• 8+ years of engineering experience building production web applications.
• Expert-level frontend depth — React + Next.js mastery (streaming, modern rendering patterns, state strategy).
• Proven ability to design high-performance, scalable, modern frontend systems with clarity and intentionality.
• Solid backend competency — ideally Golang , but strong API design fluency is required.
• Deep understanding of performance, caching, hydration, code splitting, bundling, deploy strategy, DX/UX tradeoffs .
• Product and architecture instincts — you care about what should be built, not just how .

Nice To Haves

• AI, fintech, or data-intensive product experience.
• Experience shaping design systems, frontend platforms, or reusable architecture patterns .
• Edge rendering, observability tooling, or event-driven architecture familiarity.
• Experience with relational databases (Postgres)

Responsibilities

• Lead frontend architecture and experience design — owning React/Next.js interfaces end-to-end, with a focus on performance, UX, and scalability.
• Integrate cleanly with backend services and contribute to Golang APIs when needed — not just consume them.
• Collaborate tightly with product and design on experience decisions — not just implementation .
• Influence architecture, reliability, performance strategy, and engineering standards .
• Write high-quality, clean, well-structured code — and enforce that quality in reviews.
• Act as a technical force multiplier — mentoring, unblocking, and setting the technical bar.

Benefits

• Competitive compensation + meaningful equity.
• Opportunity to define the technical foundation of a greenfield AI platform .
• A culture optimized for engineering excellence, focus, deep work, and ownership — not ticket factories.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed