Platform Engineer

Harnham; Greater London; On-site; GBP 120,000 - 140,000; Full time

Job summary

Harnham is seeking a Product Software Engineer to join an early-stage AI startup and own a cutting-edge platform used by enterprise customers. You will build LLM-enabled products from 0-1 and design scalable backend systems with API-first architecture.

You will work directly with founders and senior leadership on product direction and technical decisions, taking significant ownership as the company scales and the engineering function evolves.

Qualifications

• Experience as Product Software Engineer.
• Proven track record building LLM-enabled products 0-1.
• Strong backend experience with Node.js and TypeScript.
• Experience building API-first products and scalable platforms.

Responsibilities

• Own and scale a cutting-edge AI platform for enterprise customers.
• Design and develop scalable backend systems and APIs.
• Work directly with founders and senior leadership on product direction and technical decisions.

Skills

LLM-enabled products

Node.js

TypeScript

API-first design

Backend architecture

Product ownership

Job description

This is a unique opportunity to join a well-funded AI startup at a pivotal stage of growth. You'll become one of the earliest engineering hires, taking ownership of a cutting-edge AI platform and helping shape the future direction of both the product and engineering function as the business scales.

THE COMPANY

Our client is an early-stage AI business backed by significant investment and focused on helping enterprise organisations better understand customer behaviour through advanced AI technologies. With several large financial services organisations already engaged, the business is now moving from Proof of Concept into commercial deployment and is looking for an experienced engineer to help build and scale the platform.

THE ROLE

• Own and scale a cutting-edge AI-powered platform used by enterprise customers
• Build products around LLM and AI capabilities rather than developing the underlying models
• Design and develop scalable backend systems and APIs
• Work directly with founders and senior stakeholders on product direction and technical decisions
• Take significant ownership of architecture, delivery and platform evolution
• Help shape the future engineering function as the company grows

YOUR SKILLS AND EXPERIENCE

• Strong experience as a Product Software Engineer
• Proven experience building and launching LLM-enabled products from 0-1
• Strong backend engineering experience, ideally with Node.js and TypeScript
• Experience building API-first products and scalable platforms
• Comfortable operating in early-stage startup environments
• High levels of ownership, autonomy and commercial awareness
• React experience would be advantageous but is not essential
• FinTech or Financial Services experience would be beneficial

SALARY AND BENEFITS

• Up to £140,000 base salary
• Equity package
• Opportunity to be a key early engineering hire
• Significant ownership and influence over product development
• Direct access to founders and leadership team