Principal Machine Learning Engineer, Matching & Recommendations

Location: London, UK; on-site

Company

hirify.global develops dating, friendship and relationship products including hirify.global Date, BFF and Badoo, focused on healthy and equitable connections.

What you will do

• Define the technical strategy for AI and Machine Learning systems powering recommendations, matching, ranking and personalisation.
• Design, develop and deploy production-grade models and end-to-end ML pipelines for high-traffic environments.
• Build production AI agents using foundation models, fine-tuned LLMs, sub-agents, tools and MCP integrations.
• Develop experimentation strategies using A/B testing, offline evaluation and online measurement.
• Partner with Product, Engineering, Data Science and Analytics to solve ambiguous member and product problems.
• Mentor senior individual contributors and promote responsible AI practices covering fairness, transparency, privacy and member safety.

Requirements

• 10–15 years of relevant experience or equivalent demonstrated scope, skills and impact.
• Deep hands-on experience designing, building and deploying large-scale ML systems in production.
• Strong Python proficiency and experience with PyTorch or TensorFlow.
• Expertise in recommendation systems, ranking, retrieval, personalisation or NLP, including model architecture, features, loss functions and evaluation.
• Experience prompting and fine-tuning LLMs, building AI agents, and creating scalable data and ML pipelines with Spark, Airflow or comparable technologies.
• Ability to set technical direction, influence across teams, navigate ambiguity and mentor other engineers.

Culture & Benefits

• Values include Kind Connections, Respect, Excellence, Curiosity and continuous learning.
• Inclusive workplace with reasonable adjustments available throughout the hiring process.
• AI may support parts of recruitment, but hiring decisions are made by people; participation in AI-supported interviews is voluntary.