Junior Data Scientist

Ravelin is hiring a Junior Data Scientist for a remote role open to applicants in United Kingdom. Level rates it ; you can apply on Ravelin.

Level's read on this job

Builds AI ●●●● is how Level rates this data scientist role: the job is building AI systems.
The posting lists this role as remote.
Tools and skills the posting cites include PyTorch, scikit-learn and AI evaluation.
Level lists 4 other open roles at Ravelin.
The role was posted in the last few days.

AI in this role

PyTorchscikit-learn

ai-evaluation

Who are we?

Hi! 👋 We are Ravelin! We're a fraud detection company using advanced machine learning and network analysis technology to solve big problems. Our goal is to make online transactions safer and help our clients feel confident serving their customers.

And we have fun in the meantime! We are a friendly bunch and pride ourselves in having a strong culture and adhering to our values of empathy, ambition, unity and integrity. We really value work/life balance and we embrace a flat hierarchy structure company-wide. Join us and you’ll learn fast about cutting-edge tech and work with some of the brightest and nicest people around - check out our Glassdoor reviews.

If this sounds like your cup of tea, we would love to hear from you! For more information check out our blog to see if you would like to help us prevent crime and protect the world's biggest online businesses.

The Team

You will be joining the Detection team. The Detection team is responsible for keeping fraud rates low – and clients happy – by continuously training and deploying machine learning models. We aim to make model deployments as easy and error free as code deployments. Google’s Best Practices for ML Engineering is our bible.

Our models are trained to spot multiple types of fraud, using a variety of data sources and techniques in real time. The prediction pipelines are under strict SLAs, every prediction must be returned in under 300ms. When models are not performing as expected, it’s down to the Detection team to investigate why.

The Detection team is core to Ravelin’s success. They work closely with the Data Engineering Team who build infrastructure and the Intelligence & Investigations Team who liaise with clients.

The Role

We are currently looking for a Data Scientist to help train, deploy, debug and evaluate our fraud detection models. Our ideal candidate is pragmatic, approachable and filled with knowledge tempered by past failures.

Evaluating fraud models is hard; often times we do not even get labels for 3 months. You’ll need to use your judgement when investigating cases of ambiguous fraud and when you’re investigating the veracity of the model itself.

We have to build robust models that are capable of updating their beliefs when they encounter new methods of fraud: our clients expect us to be one step ahead of fraud, not behind. You will be given the equipment, space and guidance you need to build world class fraud detection models.

The work is not all green field research. The everyday work is about making safe incremental progress towards better models for our clients. The ideal candidate is willing to get involved in both aspects of the job – and understand why both are important.

Key Responsibilities

Build out our model evaluation and training infrastructure.
Develop and deploy new models to detect fraud whilst maintaining SLAs
Write new features in our production infrastructure
Research new techniques to disrupt fraudulent behaviour
Investigate model performance issues (using your experience of debugging models).

Requirements

Around 1 year's experience building and deploying ML models using the Python data stack (numpy, pandas, sklearn or pytorch).
Strong analytical skills.
Being a strong collaborator with colleagues outside of your immediate team, for example with client support teams or engineering.
Being skilled at communicating complex technical ideas to a range of audiences.
The ability to prioritise and to manage your workload.
Being comfortable working with a hybrid team

How we rate this

Junior Data Scientist at Ravelin rates 89 out of 100 for how much of the daily work is AI. That makes it Builds AI (AI Level 4 of 4). The level is about AI in the job, not seniority.

Classification

Builds AI. The job is building AI systems.

●●●● Builds AI80 to 100
●●●○ Works on AI60 to 79
●●○○ Uses AI40 to 59
●○○○ Little AI0 to 39

Levels come from how often the tools, models and workflows of the role are named in the posting itself. Read the description and count the AI tools, models and workflows it names.

Key facts

Junior Data Scientist is an open job at Ravelin.
Level rates this role AI Level 4 of 4: Builds AI.
The role is based in London and is marked remote.
The job was posted on November 11, 2026.
Seniority: junior.
Applications are handled by Ravelin. Apply on Ravelin

Prepare for this job

Built from this posting and from similar jobs on Level.

Skills and AI tools this role asks for

AI EvaluationPyTorchscikit-learn

Also common in data scientist jobs at this level

SQL LLM Generative AI AWS Spark Deep learning

Pay

Typical data scientist job: $167k

This posting doesn't list pay. Use the typical data scientist figure when pay comes up. See data scientist jobs

Questions you could be asked

How do you decide that one model's output is better than another's for a given task?
Walk me through how you've used PyTorch in your day-to-day work.
What are the limits of scikit-learn that you've run into, and how did you work around them?
How would you decide a model or AI system is ready to ship?
Tell me about a time a model underperformed in production. How did you find out, and what did you change?

Adapt your resume

List these exact terms on your resume: AI Evaluation, PyTorch, and scikit-learn. An applicant tracking system matches the wording, not the idea.
Attach one line of real, concrete experience to at least one of them. A tool named with nothing behind it rarely survives a human read.
Lead with what you built, trained or shipped. This role is judged on the AI system itself, not the tools around it.

Get your CV reviewed before you apply

Send your CV and the role you want next. Your review arrives by email within 3 days.

Get a free CV review Check your resume with the ATS resume checker