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I’m a results-driven multilingual professional with a track record in field sales, operations, and data-driven decision making. I have hands-on experience onboarding merchants, managing sales territories, tracking performance via CRM and Excel dashboards, and coordinating cross-functional teams to keep operations smooth and accurate. I thrive in multicultural settings and bring a structured, data-driven approach to optimize processes and report actionable insights. Throughout my career at SumUp, Invisible Expert Marketplace, and Music Maker, I’ve demonstrated strong attention to detail, reliability, and resilience in fast-paced environments. I’m fluent in English and Polish, with basic Mandarin, and I enjoy applying data-driven planning, reporting, and stakeholder collaboration to deliver measurable business results. On top of it all I am a composer that went through conservatory education.…I’m a results-driven multilingual professional with a track record in field sales, operations, and data-driven decision making. I have hands-on experience onboarding merchants, managing sales territories, tracking performance via CRM and Excel dashboards, and coordinating cross-functional teams to keep operations smooth and accurate. I thrive in multicultural settings and bring a structured, data-driven approach to optimize processes and report actionable insights. Throughout my career at SumUp, Invisible Expert Marketplace, and Music Maker, I’ve demonstrated strong attention to detail, reliability, and resilience in fast-paced environments. I’m fluent in English and Polish, with basic Mandarin, and I enjoy applying data-driven planning, reporting, and stakeholder collaboration to deliver measurable business results. On top of it all I am a composer that went through conservatory education.

Sebastian Zieliński

Data Analyst, Project Manager, Content Producer, +4

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I’m a results-driven multilingual professional with a track record in field sales, operations, and data-driven decision making. I have hands-on experience onboarding merchants, managing sales territories, tracking performance via CRM and Excel dashboards, and coordinating cross-functional teams to keep operations smooth and accurate. I thrive in multicultural settings and bring a structured, data-driven approach to optimize processes and report actionable insights. Throughout my career at SumUp, Invisible Expert Marketplace, and Music Maker, I’ve demonstrated strong attention to detail, reliability, and resilience in fast-paced environments. I’m fluent in English and Polish, with basic Mandarin, and I enjoy applying data-driven planning, reporting, and stakeholder collaboration to deliver measurable business results. On top of it all I am a composer that went through conservatory education.…I’m a results-driven multilingual professional with a track record in field sales, operations, and data-driven decision making. I have hands-on experience onboarding merchants, managing sales territories, tracking performance via CRM and Excel dashboards, and coordinating cross-functional teams to keep operations smooth and accurate. I thrive in multicultural settings and bring a structured, data-driven approach to optimize processes and report actionable insights. Throughout my career at SumUp, Invisible Expert Marketplace, and Music Maker, I’ve demonstrated strong attention to detail, reliability, and resilience in fast-paced environments. I’m fluent in English and Polish, with basic Mandarin, and I enjoy applying data-driven planning, reporting, and stakeholder collaboration to deliver measurable business results. On top of it all I am a composer that went through conservatory education.

Available to hire

I’m a results-driven multilingual professional with a track record in field sales, operations, and data-driven decision making. I have hands-on experience onboarding merchants, managing sales territories, tracking performance via CRM and Excel dashboards, and coordinating cross-functional teams to keep operations smooth and accurate. I thrive in multicultural settings and bring a structured, data-driven approach to optimize processes and report actionable insights.

Throughout my career at SumUp, Invisible Expert Marketplace, and Music Maker, I’ve demonstrated strong attention to detail, reliability, and resilience in fast-paced environments. I’m fluent in English and Polish, with basic Mandarin, and I enjoy applying data-driven planning, reporting, and stakeholder collaboration to deliver measurable business results.

On top of it all I am a composer that went through conservatory education.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Language

English

Fluent

Polish

Fluent

Chinese

Beginner

Work Experience

Field Sales Consultant at SumUp

October 1, 2025 - Present

Completed a structured field operations training program with hands-on merchant onboarding, product lifecycle management, and process optimization. Managed a sales territory of 50+ merchants, maintained CRM records, tracked onboarding progress, and provided data-driven insights for operational decisions. Supported inventory allocation and demand forecasting to reduce order errors by 15%. Collaborated cross-functionally with operations, finance, and support to resolve merchant issues and ensure smooth execution. Tracked 100+ weekly transactions to optimize onboarding workflows and drive improvements.

Master Polish Language Specialist / AI Trainer at Invisible Expert Marketplace

September 1, 2025 - October 1, 2025

Coordinated multilingual AI training projects, tracking 50+ tasks per project to ensure timely completion. Oversaw data annotation and validation for 10,000+ dataset entries, improving workflow accuracy and reducing errors by 15%. Worked with linguists, data engineers, and project managers to align objectives and resolve workflow issues. Planned resources (datasets, training materials, personnel) and conducted onboarding for new AI trainers to improve team efficiency by 20%.

Senior Operations & Supply Chain Associate at Music Maker

July 1, 2023 - September 1, 2025

Managed daily stock of 500+ SKUs, updated inventory via POS/ERP systems, and ensured optimal product availability while reducing order errors by 15%. Coordinated with purchasing and warehouse teams to ensure on-time delivery and rapid issue resolution. Analyzed sales trends and stock movements using Excel dashboards to inform restocking and promotions. Provided in-store and online customer support, mentoring staff on inventory management and POS systems, and coordinating cross-functional events to enhance customer experience.

Recruit (Trainee Soldier) at Irish Defence Forces

January 1, 2021 - April 1, 2021

Completed a 12-week intensive military training program, developing time management, resilience, discipline, and clear communication in high-pressure, diverse-team settings. Gained experience following strict protocols, safety standards, and decision-making under time-sensitive conditions, transferable to operational workflows and fast-paced roles.