Applied Machine Learning Engineer

Picnic's mission is to drive a higher quality ad-funded internet. With 70% of people finding digital ads annoying, brands are wasting ad spend on ineffective and potentially damaging ad experiences. We're a fast-growing, founder-led start-up, passionate about making digital ads work better for everyone. We are looking for our first ever Applied Machine Learning Engineer to help us build intelligent systems that power the future of digital advertising.

• Build applied ML systems that make our product smarter and more defensible
• Develop contextual categorisation of web content (e.g. automatically recognising industry categories)
• Prototype algorithms that can improve advertising outcomes, such as smarter bidding or optimisation logic
• Work closely with product and commercial teams to package outputs into demos and case studies for clients
• Collaborate with engineers to integrate ML features into production system
• Establish good practices for applied ML in the business, bringing your curiosity and drive to help us move fast while building robust foundations
• Apply modern LLM techniques to business problems:
  • Use prompt-engineering strategies to get consistent, accurate results
  • Explore augmentation methods (e.g. combining LLMs with our own data via embeddings or retrieval)
  • Run fine-tuning experiments to adapt general models to our specific domain

• Ideally, you've got 1-3 years experience in applied ML/AI (or equivalent practical experience through academic projects or early career roles)
• You're comfortable coding in Python and using ML frameworks (e.g. PyTorch, Hugging Face, scikit-learn)
• You've worked with large language models (LLMs) - not just calling APIs, but experimenting with different ways to get the best out of them:
  • Prompt engineering (designing effective prompts, chaining prompts)
  • Fine-tuning or instruction tuning models for specific tasks
  • Embedding-based augmentation (using vector search to give LLMs access to external knowledge)
  • Retrieval-Augmented Generation (RAG) or similar techniques
• You've taken messy, real-world data and turned it into useful, structured outputs
• You can show how your work had impact - whether that's a model in production, a working prototype, or an experiment that unlocked a new direction
• You're a clear communicator, able to work across functions with product managers, engineers, and commercial stakeholders
• You're excited by the prospect of being our first ML engineer, owning this area from day one and growing into a lead role quickly
• You don't need to have worked in adtech before - but if you have, that's a bonus!

• A flexible, hybrid working setup (we're usually in the office a few times a week, so being within reach of London Bridge is important)
• 33 days holiday (inclusive of Bank Holidays), plus additional Christmas shutdown
• Private Medical Insurance through Vitality
• Picnic Pension Contribution
• Inclusive Parental Leave Policy
• A great co-working space, regular socials & offsites, Picnic Thursdays, Summer Fridays and Work from Roam opportunities

Salary Range: £50-60k

• Seniority level: Entry level
• Employment type: Full-time
• Job function: Other
• Industries: IT Services and IT Consulting

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