Senior/Lead Data Scientist -Credit

PLP Group; Stockholms kommun; On-site; SEK 775,398 - 1,108,832; Full time

Job summary

Klarna in Stockholm is seeking a Senior/Lead Data Scientist to tackle technically challenging fintech modelling problems, training transformer models on long sequences of transactional events.

You will design tokenisation schemes for numerical, categorical, and temporal features, own the full model lifecycle from data prep to production, and drive architecture decisions that influence how ML is used across Klarna.

Qualifications

• Deep understanding of transformer architectures and sequence modelling.
• Experience designing tokenisation schemes for heterogeneous feature types.
• Proficiency in Python, PyTorch, SageMaker, and Airflow.
• Experience owning the full model lifecycle, from training through to serving.

Responsibilities

• Work on technically interesting modelling problems in fintech, training transformer-based models on long sequences of real-world transactional events.
• Design tokenisation schemes for numerical, categorical, and temporal features, considering vocabulary size, sequence length and information compounding.
• Own the full model lifecycle from data preparation through to production, translating research decisions into scalable systems.
• Help set the direction for how machine learning operates across Klarna and collaborate with a small, high-ownership team.

Skills

Transformer architectures

Sequence modelling

Tokenisation schemes

Python

PyTorch

SageMaker

Airflow

ML lifecycle

Job description

Senior/Lead Data Scientist -CreditJob detailsData ScienceStockholmFull-timekr 775,398 SEK - kr 1,108,832 SEK**What you will do** You will work on some of the most technically interesting modelling problems in fintech, training large transformer-based models on long sequences of real-world transactional events. You will design tokenisation schemes for numerical, categorical, and temporal features, making deliberate decisions about vocabulary size, sequence length, and information compounding. Your work spans the full model lifecycle, from data preparation through to production and you will translate research decisions into systems that set the direction for how machine learning operates across Klarna. You will be part of a small, high-ownership team where what you build has genuine impact on the products Klarna ships. Who you are* Deep understanding of transformer architectures and sequence modelling, with the ability to reason through architectural tradeoffs* Hands-on experience designing tokenisation schemes for heterogeneous feature types: numerical, categorical, and temporal* Proficiency in Python, PyTorch, SageMaker, and Airflow* Experience owning the full model lifecycle, from training through to serving in production* Comfortable working in a small, high-ownership team on open-ended technical problemsAwesome to have* Experience with Triton kernels or GPU-level optimisation* Broader ML background spanning areas beyond deep learning* Experience with large-scale transactional or financial data* Background in ML infrastructure or MLOpsPlease include a CV in English