Senior Platform Engineer — Shape a Scalable LLM AI Platform

Harnham; Greater London; On-site; GBP 90,000 - 130,000; Full time

Benefits offered by this job

Direct exposure to founders & senior领导

Clear progression as the team grows

Early-stage influence on engineering方向

Job summary

Harnham is seeking one of its first senior engineering hires to help shape an AI-driven platform for enterprise clients. You will own core product development, work with founders to set technical direction, and scale AI-powered solutions from early concept to production.

You will build features across the full stack, optimise LLM-enabled apps, and design scalable APIs while aligning with business goals and customer needs.

Qualifications

• Proven experience as Product Engineer or Software Engineer with delivered LLM-powered products.
• Strong backend skills with Node.js and TypeScript in production environments.
• Experience designing APIs and distributed systems, with exposure to frontend tech a plus.

Responsibilities

• Build and ship product features across the full stack.
• Develop and optimise LLM-enabled applications for enterprise users.
• Own retrieval augmented generation pipelines and AI integrations.
• Design scalable API-first products and backend services.
• Improve model performance, reliability, evaluation frameworks and guardrails.
• Manage token usage, response quality and cost strategies.
• Contribute to cloud infrastructure and deployment in AWS.
• Establish engineering best practices across testing, delivery and software quality.
• Collaborate with stakeholders to shape product directions and priorities.

Skills

Product Engineer

Software Engineer

LLM-powered products

Backend engineering

Node.js

TypeScript

APIs & distributed systems

AWS

Startup/high-growth experience

Communication & autonomy

React frontend exposure

Tools

AWS

Job description

Harnham is seeking one of its first senior engineering hires to help shape an AI-driven platform for enterprise clients. You will own core product development, work with founders to set technical direction, and scale AI-powered solutions from early concept to production.

You will build features across the full stack, optimise LLM-enabled apps, and design scalable APIs while aligning with business goals and customer needs.