Lead Full-Stack Engineer

Location: London, England, United Kingdom, Amsterdam, North Holland, Netherlands, Spain

Workplace: remote

Employment Type: full

Description

Complexio is building Stevie — an enterprise AI knowledge assistant that gives executives and operators a complete view of their organization through knowledge graphs. Our customers are large maritime shipping companies managing hundreds of vessels, thousands of daily emails, and complex commercial operations.

We're looking for a Senior or Lead Frontend Engineer to own Stevie's frontend. The interface is the product — it determines whether enterprise customers trust the intelligence, get value quickly, and come back. You'll shape all of that.

Why This Role

Enterprise AI UX is unsolved. You won't copy patterns — you'll create them. Citations from knowledge graphs, streaming AI responses that feel trustworthy, confidence indicators on operational intelligence.

You own the full frontend. No separate frontend team. You are it — with real influence on product direction and architectural decisions.

Flat org, real impact. Domain owners have authority. Engineering decisions are made by engineers, not managers.

You'll own the full frontend — conversational AI interfaces, content feeds, document generation, collaborative features. The product is evolving fast and you'll shape what gets built and how.

Requirements

Must-haves

5+ years of frontend experience in production. You understand rendering models, performance characteristics, and architectural patterns deeply.

• Strong product sense. You push back when the UX doesn't make sense. You've shipped real user-facing products.
• Real-time/streaming UI experience. WebSockets, SSE, or similar live data patterns.
• Comfort with ambiguity. You take vague problems and turn them into concrete frontend solutions.
• You ship. End-to-end — prototype to production to iteration on feedback.

Strong signals

• Enterprise/B2B SaaS. You know the difference between consumer UX and building for a CFO who needs to trust a number.
• AI product experience. Latency UX, citation rendering, hallucination presentation.
• Design sensibility. Polished interfaces without a designer in the room.
• Backend literacy. You can read a REST API and collaborate with backend engineers on data contracts.
• Startup experience. Small teams, multiple hats, fast without cutting corners.

How We Work

• Direct communication. Honest feedback, hard questions, no hiding behind process.
• Ownership over tasks. You're asked what you shipped and learned, not to fill out status reports.
• Speed with quality. We ship fast because we scope well. Customer feedback cycles are weeks, not quarters.
• AI-augmented workflow. We use AI tools extensively and expect you to be comfortable with AI-assisted development.