AI Engineer, Personalisation & Recommendations

Calyptus; Greater London; On-site; GBP 70,000 - 120,000; Full time

Job summary

Calyptus is recruiting on behalf of a client for a role owning the algorithms that decide what users see. You’ll design, build and ship end-to-end recommender and personalisation systems, collaborating with a Data Engineer and a small senior team to ship features quickly.

You’ll bring a strong ML/Data Science foundation and proven experience in productionising recommendations at consumer scale, with an emphasis on agentic tooling and modern LLM approaches to drive outcomes.

Qualifications

• Experience building and productionising recommendation systems shipped to real users.
• Solid foundation in machine learning and data science beyond API usage.
• Experience at consumer platforms where behavioural data is core asset.
• Comfortable operating as an IC in a small, highly autonomous team.
• Familiar with agentic tooling and LLM approaches.

Responsibilities

• Design and productionise recommendation engines and personalisation algorithms for a consumer-facing platform.
• Take models from experiment to production, owning their performance.
• Decide which signals matter and collaborate with data engineers to model them.
• Run experiments and measure real user impact, not just offline metrics.
• Apply modern agentic and LLM-based approaches to improve outcomes.

Skills

Recommendation systems

Machine Learning

Data Science

IC in small autonomous team

Agentic tooling

Job description

This role is being recruited by Calyptus on behalf of one of our clients.

Calyptus is a specialist recruitment partner helping startups and high-growth technology companies hire across engineering, product and design.

What to expect

• We’ll review your application and, if your experience is a strong match, one of our team will be in touch
• We’ll support you throughout the interview process and keep you updated at each stage
• If this particular role isn’t the right fit, we may consider you for other relevant opportunities with our clients

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You'll own the algorithms that decide what every user sees. That means designing, building and shipping recommendation and personalisation systems end-to-end — from problem framing and feature design through to production deployment, monitoring and iteration. You'll work alongside a dedicated Data Engineer who builds the pipelines and architecture underneath you, and you'll report into a small, senior team where your work goes live quickly.

What you'll do

• Design and productionise recommendation engines and personalisation algorithms for a consumer-facing platform
• Take models from experiment to production, and own their performance once they're there
• Decide what signals matter, and work with the Data Engineer to get them modelled and available
• Run experiments and measure real impact on user behaviour, not just offline metrics
• Apply modern agentic and LLM-based approaches where they genuinely improve outcomes

What we're looking for

• Demonstrable experience building and productionising recommendation systems or personalisation algorithms for apps or websites — shipped, live, used by real users
• A genuine Machine Learning and Data Science foundation — you were solving these problems before the ChatGPT era, not just calling APIs
• Background from a consumer platform where behavioural data is the core asset — social platforms, marketplaces, travel, large-scale consumer tech
• Comfortable operating as an IC in a small team with high autonomy
• AI-native in practice: fluent with agentic tooling and able to use it to move faster

Nice to have

• Experience applying agent-based approaches to recommendations or personalisation
• Experience at a company that scaled from Series B through C/D/E

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Genuine opportunities

Every role advertised by Calyptus is a live position we’re actively recruiting for. Some clients prefer to remain confidential during the early stages of the hiring process. When that’s the case, certain company details may be shared later in the process.

Why work with Calyptus?

• Access opportunities with ambitious startups and high-growth technology companies
• Direct support from experienced specialist recruiters
• Honest feedback and clear communication throughout the hiring process
• Long-term career support, not just a single job application