Senior Data Scientist

IDT Corporation; Województwo mazowieckie; Hybrid; PLN 591,000 - 748,000; Full time

Benefits offered by this job

Remote/hybrid work

Long-term growth

Competitive salary

Training & conferences

English classes

Referral program

Job summary

IDT Corporation is expanding its AI Lab and seeking a hands-on Senior Data Scientist to design, build, and deploy ML models from scratch for fraud prevention, payment risk, and personalization. You will own the full modeling lifecycle from problem framing to production monitoring and continuous improvement.

The role requires 5+ years of hands-on DS/ML experience, strong Python and DL skills, and fluency in English to collaborate with an international team.

Qualifications

• 5+ years hands-on Data Science / ML experience, building/new models from scratch and delivering to production with measurable impact.
• Fluent English (B2+) written and spoken for technical discussions with an international team.
• Deep understanding of statistics, probability, validation methodologies; handling class imbalance, calibration and anomaly detection.

Responsibilities

• Design and build new models from ground up for anti-fraud, risk assessment and personalization; maintain rigorous validation to prevent leakage.
• Partner with Data Engineering and MLOps to operationalize models in production (batch and real-time); build training, experiment tracking, and drift monitoring pipelines.
• Design A/B tests and statistical evaluations to measure model performance against business metrics (fraud reduction, acceptance rates, latency).
• Explore emerging techniques (LLMs/GenAI, graph-based methods) and establish engineering best practices; mentor team members.

Skills

ML from scratch

Production deployment

English proficiency

Experiment design

Cross-functional collaboration

Education

Bachelor's degree in quantitative field

Tools

Python (Scikit-learn, Pandas, NumPy)

PyTorch

TensorFlow

SQL

MLflow

ClearML

Job description

IDT is expanding its AI Lab and seeking a hands-on, highly experienced Senior Data Scientist with a proven track record of building new ML models from scratch and deploying them into real-time production. You will tackle complex problems across fraud prevention, payment risk, transaction scoring, personalization, and financial forecasting using large-scale transactional datasets. You will own the full modeling lifecycle — from problem framing through to production monitoring.

Key Responsibilities:

• ML & Predictive Modeling: Design and build new models from the ground up (gradient boosting, neural networks, ensembles, anomaly detection) for anti-fraud, risk assessment, and personalization; maintain rigorous validation practices to prevent data leakage and overfitting.
• End-to-End & MLOps: Partner with Data Engineering and MLOps to operationalize models in production (batch and real-time/low-latency); build training, experiment tracking (MLflow), and model/data drift monitoring pipelines.
• Experimentation & Business Impact: Design A/B tests and statistical evaluations to measure model performance against key business metrics (reduced fraud losses, transaction acceptance rates, decision latency).
• R&D & Technical Leadership: Explore emerging techniques (LLMs/GenAI, graph-based methods), establish engineering best practices, and mentor fellow team members.

Requirements (Must-Have):

• Experience: 5+ years of hands‑on experience in Data Science / ML, with a strong focus on designing and building new ML models from scratch and delivering them into production with measurable business impact.
• English: B2+ (Upper-Intermediate or higher) — fluent written and spoken communication for technical discussions and daily collaboration with an international team.
• Math & Modeling Foundations: Deep understanding of statistics, probability, and validation methodologies; practical experience handling class imbalance, model calibration, and anomaly detection.
• Tech Stack:
  • Python: Advanced proficiency (Scikit-learn, Pandas, NumPy);
  • Deep Learning: Hands‑on experience with PyTorch or TensorFlow;
  • SQL: Complex queries and large-scale data manipulation;
  • MLOps Tools: Experiment tracking and model lifecycle management (MLflow, ClearML, etc.).
• Education: Bachelor’s degree in Computer Science, Mathematics, Statistics, Engineering, or a related quantitative field.

Nice-to-Have:

• Domain experience in FinTech, Payments, or Fraud Prevention: real-time transaction scoring and low-latency inference.
• Experience with cloud data platforms (Snowflake), Feature Stores, and event-driven architectures.
• Background in time-series forecasting, graph neural networks, Explainable AI (XAI), or applied LLM solutions.
• Master’s degree or Ph.D. in a quantitative discipline.

We offer you:

• Remote b2b or hybrid (Belarus-Moldova) work opportunity!
• Stable job with long-term growth perspective
• Competitive salary with annual performance review
• Really good hardware
• An exciting and challenging job with talented people around
• Continuous learning and career growth opportunities
• Compensation for professional training, seminars, and conferences
• Referral program - get rewarded for helping us grow the team with talented people
• Company-supported English classes to enhance your professional growth
• More perks for the Minsk and Chisinau office employees

A few words about us:

IDT Corporation is a global communications company founded in 1990 and headquartered in Newark, New Jersey. We are industry leaders in prepaid communication and payment services and one of the largest international voice carriers. We are listed on the NYSE, employ over 1800 people across 20 countries, and have over $1.5 billion in revenues. IDT is not ”another big IT corporation”— we encourage and support in-house entrepreneurs in developing their ideas into business actions. Our flagship brand, BOSS Revolution, offers Money Transfer, International Calling, and Mobile Top-Up services and supports IDT’s mission of enabling people to keep in touch and share resources with family and friends worldwide. If you're looking for a company that will give you the maximum flexibility in choosing a location to work, this opportunity is for you! We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses and identifying potential inconsistencies or verification signals in application materials based on available information. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.