Data Scientist

About this role

Data Scientist

🌍 UK (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

🦸‍♀️ 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 Data 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 for customer feedback tasks, contributing to our custom fine-tuning pipelines and running experiments with rigour and clear documentation.

- Build and maintain LLM-powered features including retrieval pipelines, reranking systems, and insight generation — with support and guidance from senior team members.

- Contribute to evaluation frameworks: help build test sets, define metrics, and assess model quality across classification, extraction, and generative tasks.

- Work on semantic search and retrieval, developing a strong working understanding of embedding-based approaches and the methods that go beyond them.

- Write clean, well-tested code and collaborate with Engineering on model integration, data pipelines, and monitoring.

- Work with the wider Data Science team to translate business and product requirements into practical ML experiments and solutions.

- Stay close to relevant research and bring useful ideas from the literature into team discussions and experiments.

🧰 What you’ll need:

-  A solid working knowledge of transformer architectures and how they are applied in NLP tasks.

- Proficiency in PyTorch, including training loops and standard model fine-tuning workflows; exposure to parameter-efficient techniques such as LoRA is a plus.

- Experience working with real-world text data across tasks such as classification, extraction, embeddings, or search — at a meaningful scale.

- Some exposure to instruction fine-tuning or model serving, with an interest in going deeper.

- A grounding in classical ML and statistics, and the instinct to reach for simpler methods when warranted.

- Familiarity with GenAI and agentic patterns, even if hands-on production experience is still developing.

- Clear communication skills and the ability to explain technical work to colleagues across functions.

- Genuine curiosity about AI and a habit of experimenting — you learn by doing.

- Good ownership instincts: you follow problems through rather than passing them on.

➕It would be a bonus if you:

- MSc in Computer Science, Machine Learning, AI, Data Science, Computational Linguistics, or a closely related STEM field.

🔎 Our Hiring Process

1. Let’s introduce ourselves – you’ll complete an introductory asynchronous interview - we’d love to learn more about you, your ambitions, and what you’re looking for in your next step.

2. Get to know your would-be manager – you’ll have a call with Aji, our Chief Scientist, to learn more about the role and show off your experience.

3. Show us how you work – you'll complete a short take home assignment

4. Get to know your would-be team – You'll meet a mix of people who you'll be working closely with from the Data Science, Engineering and Product teams.

5. How our values and your career goals align – you’ll have a call with our cofounder to learn more about life at Chattermill and ensure we’re the right place for your next stage of growth.

Our Perks

🤸🏽‍♂️ Flexibility & Work Setup

- Flexible working in a choice-first environment - we trust the way you want to work!

- Work-from-home allowance to set up your ideal workspace

🌴 Time Off

- 25 days holiday + local bank holidays, plus an extra day for each year of service

- Your birthday off

🌱 Growth & Ownership

- Annual learning & development budget to support your growth (increasing over time)

- Equity options — share in the company’s success

💚 Health & Wellbeing

- Monthly health & wellbeing budget, increasing with length of service

- Optional private healthcare plan

- Life assurance & income protection (location dependent)

- Employee Assistance Programme (location dependent) for extra support when you need it

- Enhanced family leave (location dependent), plus fertility and neonatal leave

🌆 Office Perks

- If you’re in London, a dog-friendly office with great classes, events, and a rooftop terrace

💖 Our Values

- We are obsessed with experience – We take our mission to rid the world of bad Customer Experience seriously, and we practice what we preach.

- We believe in the power of trust – Whether it's with each other, our customers, partners, or other stakeholders, we always communicate with openness and trust.

- We act as responsible owners – Whether it's about the company, a team, a project, or a task, having the freedom to make decisions in our area of responsibility is a crucial driver for us.

- We share a passion for growth & progress – On every level, we’re motivated by taking on new challenges – even if they seem out of reach. We recognise that we are learning machines and we always seek to action feedback and improve collectively.

- We set our ambitions high but stay humble – We've come together to build a product and a category that’s never been seen before. While we're an ambitious bunch with lofty goals, we…