ML Engineer at Passionfruit

Jack & Jill; Greater London; On-site; GBP 80,000 - 110,000; Full time

Job summary

A Series A AI startup in London is seeking a Senior ML Engineer to lead the design and implementation of production ML systems that automate marketing operations for top brands. The ideal candidate will have 4-8 years of experience in machine learning, with strong Python skills and the ability to solve complex technical challenges. This role offers the chance to take ownership of architecture decisions in a fast-paced environment, driving innovation in the marketing sector.

Qualifications

• 4-8 years of hands-on experience building and shipping production ML systems.
• Strong engineering fundamentals in Python and API development.
• Proven track record of solving ambiguous technical challenges.

Responsibilities

• Develop and deploy production-grade ML/LLM systems and workflows.
• Integrate models with live enterprise data sources like Google Ads and various CRMs.
• Build and refine evaluation frameworks and fine-tuning processes.

Skills

Production ML systems

Python

API development

RAG and LLM agents

Adtech

Marketing analytics

Job description

Job Title

ML Engineer

Company Description

Passionfruit - Series A AI startup ($13.3M raised) backed by Seaya and Playfair

Job Description

As the most senior ML Engineer on a high‑impact team, you will design and ship production LLM systems that automate complex marketing operations for Fortune 500 clients like PepsiCo and HSBC. You will build agentic workflows with persistent memory and tool use, transforming how global brands analyze data and execute campaigns.

Location

London, UK

Why this role is remarkable

• Take meaningful ownership of architecture and model selection as the most senior ML engineer on a small, elite technical team.
• Work at a well‑funded Series A startup ($13.3M raised) backed by top‑tier investors like Firstminute Capital and Seaya Ventures.
• Directly impact the marketing operations of some of the world's largest brands, moving them from manual "gut‑feel" processes to AI‑native precision.

What you will do

• Develop and deploy production‑grade ML/LLM systems and agentic workflows with persistent memory and sophisticated tool‑use capabilities.
• Integrate models with live enterprise data sources including Google Ads, GA4, Meta Ads, and various CRM and analytics platforms.
• Build and refine evaluation frameworks, retrieval systems, and fine‑tuning processes specifically optimized for the marketing domain.

The ideal candidate

• Possesses 4-8 years of hands‑on experience building and shipping production ML systems, with deep expertise in RAG and LLM agents.
• Demonstrates strong engineering fundamentals in Python and API development, with the ability to thrive in a fast‑paced, high‑ownership environment.
• Brings a proven track record of solving ambiguous technical challenges, ideally with exposure to adtech, marketing analytics, or Elixir.