Yevhen

YEVHEN KUPRIIUK
Back-End Engineer
yevhenkupriiuk​@gmail.com [open contact info](look above in the "contact info" section)
Novovolynsk [open contact info](look above in the "contact info" section)

PROFILE
Back-End Engineer with 3 years of commercial experience delivering scalable backend systems in FinTech
and iGaming domains. Strong expertise in Java ecosystem (Spring, Hibernate, JPA) and experience with
JavaScript/TypeScript backend (Express.js, Nest.js). Focused on system reliability, performance
optimization, and feature delivery across distributed systems. Comfortable working with SQL/NoSQL
databases, messaging systems, and API-driven architectures. Seeking a Middle Back-End Engineer role to
contribute to high-load, product-driven systems.

EMPLOYMENT
Java Backend Developer, Suntech Innovation 10/2024 – Present | Remote
Development and support of backend services in Java and Groovy
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Responsibility for 3 production services, including bug fixing and incident handling
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Participation in production support, including handling P1 incidents and hotfixes
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Development of backend features and maintenance of existing business logic
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Work on a TypeScript-based service introduced into the ecosystem
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Integration with external providers
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Direct interaction with provider APIs
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Data collection and processing for internal usage
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Building internal models based on provider responses
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Development of simulation tools for provider behavior
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Implementation of a bet placement simulator
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Reproduction of real business flows for testing and validation purposes
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Event-driven processing using Kafka (consumers/​producers, debugging flows)
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Service-to-service communication using gRPC
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Performance and reliability: SQL query optimization
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Investigation of production issues via Kibana /​logging systems
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Participation in release process: Release candidate preparation, Deployment and hotfix support
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CI/​CD pipelines using Jenkins
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Working with containerized environments using Kubernetes (Lens)
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Mentoring newcomers (informal guidance during onboarding)
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Software Engineer, WWG 03/2024 – 09/2024 | Ukraine
Stack: Spring /​Hibernate /​Express.js /​Nest.js
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Developed backend services using Java (Spring, Hibernate) and JavaScript (Express.js, Nest.js) across
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multiple concurrent projects
Designed and implemented AI-assisted questionnaire system
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Users submitted data via Google Forms
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System generated structured AI-based responses from input data
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Built and maintained lead processing pipelines and integrations
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Integrated advertising sources for lead collection
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Automated data flows using Pipedream
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Developed and integrated ERP-related backend functionality
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Data synchronization between internal systems and business workflows
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Performed root-cause analysis of production issues, resolving incidents and improving system stability
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Implemented an in-house email validation service, reducing external validation costs by -20%
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 Delivered features end-to-end: implementation, testing, and production release coordination across
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parallel projects
Java Backend Developer, Life Insurance Project (NDA) 06/2023 – 03/2024 | Germany
Worked on enterprise insurance systems using Java 8/​11/​15 and Spring ecosystem
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Maintained and extended legacy J2EE components in production systems
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Participated in Agile planning, estimation, and delivery processes
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Supported business-critical applications with focus on reliability and compliance
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Communicated with stakeholders regarding system behavior and delivery status
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Perl/Java Developer, PortaOne 12/2022 – 05/2023
Developed internal notification and reminder system integrated with Slack API
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Adapted to Perl-based backend after Java onboarding, working with legacy architecture
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Implemented automation tools for task tracking and reminders across teams
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Contributed to internal workflow optimization and process automation
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SKILLS
Java Development Spring Databases
Java Core, Java 8+, JDBC,
• Spring Core
• MySQL, SQLite, PostgreSQL,
JSP, JSTL, JPA Spring Boot
• MongoDB, FlyWay, Liquibase,
Groovy, Gradle, Kafka,
• Spring MVC
• Redis
Jenkins, Elastic (Kibana) Spring Data JPA
Version Control Systems
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Design Patterns, Maven, Spring Security
Git, Gerrit, SVN
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Tomcat, JUnit, Lombok,
Postman, Docker, XML, JSON Agile Methodologies
AWS S3 bucket
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Scrum, Kanban

Web Development Project Management Tools
CSS, HTML, SOLID, TDD, CRUD, Gemini, Jira
Grpc
Soft Skills
Teamwork, Problem-solving
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Communication, Adaptability
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LANGUAGES
English Ukrainian Polish
Upper-Intermediate Native Basic

ACHIEVEMENTS
Performance Optimization, Internal
Designed and implemented a simulation tool for provider behavior, increasing RPS from 120 to 500
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through performance optimization and database normalization.
System Architecture Improvement, Internal
Developed a GRPC-based service interaction layer enabling cross-service communication and bet
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placement logic improvements.
Built an internal multi-instance database interaction tool used across environments for controlling
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external service behavior.
Infrastructure & Efficiency, Internal
Reduced integration test execution time from 20 minutes to 6 minutes through test optimization and
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infrastructure improvements.
Delivered features for First Line Support (FLS), improving operational response efficiency.
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Leadership & Mentoring, Internal
Conducted technical interviews for junior developers and participated in mentoring activities.
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