Senior Machine Learning Scientist
Chattermill
| Company | Chattermill |
| Category | Data & Analytics |
| Location | UK |
| Remote | Remote |
| Employment | Not stated |
| Level | Senior |
| Salary | Not stated by the employer |
| Posted | 8 Apr 2026 |
| Last verified | 30 Jul 2026 |
| Source | Employer career page (ashby) |
Description
Senior Machine Learning Scientist
🌍 UK or Poland (Remote or Hybrid, it’s up to you!)
💰 Dependent on experience
📈 Be part of our success with the opportunity to join our company equity scheme
Our Perks
❤️ Monthly Health & Wellness budget, increasing with length of service
📚 Annual Learning and Development budget, increasing with length of service
🤸🏽♂️ Flexible working in a choice-first environment - we trust the way you want to work!
🖥️ Work From Home Allowance
🌴 25 Holiday Days + your local bank holidays, plus an extra day for every year of service
🎂 Your birthday off
🍼 Enhanced Family Leave (UK Only), Fertility Leave, and Neonatal Leave
⚕️ Optional Healthcare Plan
🛟 Life & income protection (Location dependent)
🤝 Employee Assistance Programme (UK Only)
📈 The opportunity to share in the company’s success through options
🌆 If you’re in London, a dog-friendly office with great classes, events, and a rooftop terrace
🦸♀️ The Role 🦸♀️
Our mission is to help large successful brands like Uber, Amazon, Wise, HelloFresh (and more!) put their customers at the centre of everything they do. Using best-in-class tech in a fast-developing AI space, our Customer Experience Intelligence platform continuously analyses explicit and implicit feedback to enable our clients to identify what they should do next.
We're hiring a Senior Machine Learning Scientist to join the team and help build and ship the next generation of that stack.
👉 What you'll be doing:
Unlike many companies, we use our own custom models, specialised for customer feedback, across various parts of the stack: extraction, retrieval, reranking, summarisation, and sentiment analysis. We are also pragmatic and understand that the right solution can be a combination of off-the-shelf LLMs, bespoke fine-tuned models, and sometimes techniques that utilise no LLM at all.
This means you will:
- Train, evaluate, and iterate on ML models and agentic systems for customer feedback, including owning our custom fine-tuning pipelines. Run experiments end-to-end, track results rigorously, and make clear recommendations on what to ship, iterate, or retire.
- Build and maintain LLM-powered features: retrieval pipelines, reranking systems, insight agents, data mining agents, and automated taxonomy generation.
- Design and run robust evaluation frameworks: build test sets, define metrics, evaluate non-deterministic systems, handle class imbalance, and automate checkpoint comparisons.
- Improve and extend semantic search and retrieval, evolving from embedding-based approaches toward more advanced methods.
- Write production-quality code and collaborate closely with Engineering on productionisation, model serving, data pipelines, and monitoring.
- Work with Product and Commercial teams to translate business needs into practical ML solutions, and support client evaluations and accuracy benchmarking.
- Mentor team members, review code and research, and bring relevant advances from the literature into the product.
🧰 What you’ll need:
- A deep working knowledge of transformer architectures.
- Strong PyTorch skills, with the ability to write custom training loops, modify model architectures, and debug issues at the tensor level. Ideally, experience with parameter-efficient fine-tuning techniques such as LoRA
- Extensive experience working with large-scale, messy real-world text data, including classification, extraction, embeddings, re-rankers, clustering, and search.
- Experience in instruction fine-tuning and serving language models, familiarity with frameworks such as vLLM, DeepSpeed, or similar tools
- A solid grounding in classical ML and statistics, and the judgement to choose simpler methods when they’re the right solution.
- Practical experience building with GenAI and agentic patterns.
- Excellent communication skills and confidence
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