Lead Engineer - Node.js, React Native, AI Agents

Job description

Lead Engineer | Node.js, React Native, AI Agents

Location: London / hybrid preferred, or remote from Central & Eastern Europe

Level: Mid-to-Senior, hands-on Lead

Employment: Full-time, permanent

About the company

We are an early-stage UK product company building an AI-powered platform focused on professional relationships and network intelligence.

The product combines a social graph, relationship data and an AI agent that helps users identify relevant people, understand their network and strengthen important connections.

We are looking for a Lead Engineer / Founding Senior Engineer who will own the technical architecture, write production code and help grow the engineering team.

This is a hands-on engineering role, not a pure management position.

Tech stack

- Node.js / TypeScript / Express

- React Native + Expo

- MongoDB Atlas

- Atlas Vector Search + BM25 / hybrid retrieval

- OpenAI / custom LLM tool-calling agents

- AWS EC2, Cognito, S3

- Docker, Nginx

- GitHub Actions / CI/CD

Responsibilities

- Own technical architecture and production infrastructure

- Ship features across backend, mobile and AI agent layers

- Build and improve LLM agents, prompts, tool-calling flows and evaluation

- Mentor engineers and establish strong engineering practices

- Implement privacy-by-design and GDPR requirements

- Build and use synthetic data for development, testing and model evaluation

- Own CI/CD, monitoring, secrets management and incident response

- Own application and infrastructure security

- Secure AI agents against prompt injection, data leakage and unintended tool actions

- Work directly with the Founder on product and architecture decisions

Must-have

- 4+ years of professional software engineering experience

- Strong Node.js / TypeScript backend experience

- Experience owning real production systems

- Comfortable across backend, frontend/mobile and infrastructure

- MongoDB or similar document database experience

- Hands-on experience building LLM agents and prompting systems

- Experience with agent tool usage and evaluation

- Practical GDPR and data privacy knowledge

- Strong security fundamentals

- Understanding of AI-agent risks such as prompt injection, data leakage and unintended actions

- Experience working with synthetic data

- Production deployment, monitoring and incident-response experience

- Previous mentoring or technical leadership experience

- Comfortable with ambiguity and a fast-moving startup environment

Nice-to-have

- React Native / Expo

- RAG / vector search

- AWS Cognito

- Previous Tech Lead, CTO or founding engineer experience

- Application security / pentesting background

- Experience securing LLM / AI-agent applications

Compensation

Competitive salary + equity depending on experience and location.

We are looking for someone interested in a long-term role and growing together with the company, not a freelance or short-term contract position.