Senior Full Stack Engineer (Backend-Leaning)

Early Series A AI Startup

Remote (UK) | Competitive Salary + Strong Equity with potential early realisation (12–18 months)

We are working with a rapidly scaling, early Series A AI startup building a next-generation platform that enables enterprises to move from AI concept to production-grade systems in weeks, not months.

The business is already live with enterprise customers, generating revenue, and scaling fast, with strong funding and significant upside potential.

This is a backend-leaning Senior Full Stack Engineer role, ideal for someone who wants deep ownership of core systems while still contributing across the full stack.

The Opportunity

You will join a small, highly technical engineering team building the core infrastructure behind an AI-native platform designed for real-world enterprise deployment.

You’ll own critical parts of the product end-to-end — from backend architecture to frontend delivery and help shape how AI systems are built and operated at scale.

This is a high-ownership, low-process, high-impact environment where engineers directly influence product direction.

Key Responsibilities

• Own and deliver end-to-end product features (frontend, backend, and deployment).
• Design and build scalable Python backend services (FastAPI or similar).
• Architect and maintain AI-driven systems (async workflows, streaming, state-heavy systems).
• Build high-quality frontend features using TypeScript, React, Next.js.
• Lead technical decision-making across APIs, data models, and system design.
• Improve engineering quality through testing, CI, performance, and code reviews.
• Collaborate closely with Product, Design, and AI/ML teams.
• Contribute to mentoring and raising technical standards across the team.

Tech Stack

• Python (FastAPI or similar)
• Async programming & API design
• Distributed / event-driven systems
• TypeScript
• React / Next.js
• PostgreSQL (schema design, performance, migrations)
• OAuth / OIDC
• JWT
• RBAC / ABAC
• LLM integrations
• Tool/function calling
• Streaming architectures
• Vector databases
• Agent-based systems

What We’re Looking For

• Strong experience as a Senior Full Stack Engineer (backend-leaning).
• Deep expertise in Python backend systems (FastAPI or similar).
• Strong ability with TypeScript + React.
• Experience building SaaS products in production environments.
• Understanding of authentication, permissions, and secure system design.
• Exposure to or strong interest in AI-native development and LLM systems.
• Strong product mindset with ability to operate in ambiguity.
• Comfortable taking ownership of backend architecture and core services.