Sergii

Sergii Smagin | [open contact info](look above in the "contact info" section) | [open contact info](look above in the "contact info" section) | [open contact info](look above in the "contact info" section)
Backend Software Engineer with 5+ years of experience building scalable APIs and distributed systems using Java and
Spring Boot. Experienced in delivering production-ready features, improving system reliability, and collaborating in
cross-functional teams. Interested in building customer-facing enterprise systems with real-world impact.

CORE COMPETENCIES
Java, Spring Boot, .NET, C#
REST APIs, Microservices, Event-driven architecture, Kafka, Redis
PostgreSQL, MySQL, MS SQL, SSAS, SSIS
AWS (EC2, RDS, S3), Docker, CI/CD (GitHub Actions)

PROFESSIONAL EXPERIENCE
Independent Contractor | Software Engineer (Canada, Jan 2023 - Present)
ReSkill Calgary is an ecosystem builder with a mission to help integrate highly skilled STEM immigrants into the Calgary tech space.
● Contributed to building a full-stack platform used by 10,000+ monthly users.
● Developed backend APIs and business logic for event discovery, registration, and cloud storage (AWS).
● Collaborated in a team of 4 engineers to deliver the product in under 3 months.
● Stack: Java, Spring Boot, Docker, Maven, GitHub Actions, MySQL, AWS (EC2, RDS, S3).
Outlier helps the world’s most innovative companies improve their AI models by providing human feedback.
● Evaluated and improved AI-generated code quality (Java, Python, SQL).
● Identified edge cases and correctness issues in algorithmic solutions.
● Stack: Java, Python, SQL.

Backend & Distributed Systems Projects
● Built and maintained backend services using Java and Spring Boot, supporting scalable web applications and APIs.
● Designed event-driven communication between microservices (Kafka) to improve system decoupling and reliability.
● Improved data processing performance by 82% (17 min to 3 min) by refactoring legacy pipelines.
● Developed CI/CD pipelines with GitHub Actions, reducing deployment time by ~35%.
● Stack: Java, Spring Boot, Docker, Gradle, PostgreSQL, MySQL, Redis, Kafka.

ROSHEN Confectionery Corporation | Software Engineer (Ukraine, Apr 2021 - Sep 2022)
ROSHEN is one of the world’s largest confectionery manufacturers (ranks 27 in the Global Top-100 Candy Companies ranking).
● Built backend systems for financial analytics and ERP integrations.
● Reduced report generation time from 3+ hours to 4 minutes (~50x improvement).
● Designed data ingestion pipelines from multiple sources, reducing processing time from days to under 1 hour.
● Created a system for monitoring compliance with company standards using AI-based photo recognition of SKUs.
● Stack: .NET, C#, MS SQL, SSAS, SSIS, BAS ERP.

Agrarian System Technologies | Software Engineer (Ukraine, Jan 2019 - Apr 2021)
AST is an agrarian enterprise that manages a land bank spanning over 50,000 hectares and features modern elevator complexes,
enabling the total annual transshipment of late grains and industrial crops with a volume exceeding 500,000 tons.
● Developed backend features for ERP system (Java + MS SQL).
● Automated reporting workflows, reducing manual effort by 70%.
● Built internal tools that reduced support requests by ~30%.
● Stack: Java, MS SQL, BAS ERP.

EDUCATION
Master’s Degree in Computer Systems and Network Engineering
National Technical University of Ukraine 'Kyiv Polytechnic Institute' (Ukraine)
One of the oldest and largest technical universities in Ukraine and Europe.