Senior Backend / Full-Stack Engineer (E5/E6 Level) – AI-Native Startup – Strong Comp + Equity

My client, a high-growth AI-native startup based in Central London, is looking for an exceptional Senior Backend or Full-Stack Engineer to join their core engineering team.

This is a rare opportunity to join an engineering-led company at an early but high-traction stage, working directly on business-critical AI and communications infrastructure used in real-world production environments.

The company operates as a genuinely AI-native engineering organisation. AI tooling, LLM-powered workflows, and rapid iteration are deeply embedded into how the team builds products day-to-day. The engineering culture is highly execution-focused, fast-moving, and extremely hands-on.

They are specifically looking for engineers operating at roughly Meta E5/E6 level (or equivalent from companies such as Meta, WhatsApp, Shopify, Stripe, Revolut, Deliveroo, etc.) with strong product engineering instincts and deep technical ability.

The ideal candidate is a highly capable senior engineer who combines startup velocity with strong systems thinking and enjoys operating in high-ownership environments.

You will work directly alongside the CTO (ex-JP Morgan) and Head of Engineering (ex-Meta) on core architecture, product direction, and scaling challenges.

Requirements:

• 5+ years of software engineering experience in high-performance production environments

• Strong backend or full-stack engineering skills

• Experience building scalable distributed systems and production infrastructure

• Strong product engineering mindset with ability to move quickly and own features end-to-end

• Experience with TypeScript / Node.js strongly preferred

• Experience with modern frontend frameworks (React / Next.js) is a plus for full-stack candidates

• Strong understanding of system design, reliability, scalability, and observability

• Experience in startups or fast-paced product environments is highly desirable

• AI-native mindset — comfortable leveraging AI tooling and rapid iteration workflows

• Strong communication skills and ability to operate autonomously

• European language skills required (Spanish strongly preferred)

• Must already have right to work in the UK or Europe — visa sponsorship is not available outside Europe

• Must be willing to work fully onsite from the company’s Central London office

Tech Environment:

• TypeScript, Node.js, React, Next.js

• AI-native workflows and internal LLM tooling

• Distributed systems and real-time infrastructure

• OpenSearch, SingleStore, Trigger.dev, Axiom

• Modern cloud-native infrastructure and observability stack

What they offer:

• Excellent compensation + meaningful equity

• High-ownership environment with direct impact on product and architecture

• Small, elite engineering team

• Direct collaboration with experienced leadership (ex-Meta / ex-JP Morgan)

• Centrally located Marylebone office

• Premium gym membership

• Fast-moving, ambitious startup environment with strong backing

This role is ideal for engineers who want to build quickly, solve difficult technical problems, and help shape the foundations of a high-growth AI company from an early stage.

To apply, please send your CV or contact gala.santaballa@mondrian-alpha.com directly.