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Yaroslav Kiriak
Java Senior Software Engineer

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Telegram: @believe_in_debug

About me
Senior Software Engineer with 8+ years of experience in team leading, splitting the monolith, building
AWS cloud-based, cross-regional and high-performance systems, database schema designing,
assistance with intricate banking, corporate and enterprise systems, and setting up CI/CD.

Main specialization: building high-load distributed event-driven systems, developing RESTful Web
Services with Spring / JPA / Relational, NoSQL DBs / AWS.


Summary
● Professional experience with Java 8-21.
● Experience with such technologies as Spring (Core, Boot, Data JPA, Data MongoDB, Security,
Batch, Integration, Web MVC, Web Flux), Quarkus, Vert.x, JPA, Hibernate, EclipseLink,
JPQL/HQL, ActiveMQ, Play Framework, Vaadin, Flyway, Jackson, Apache POI, Logback,
MapStruct, Lombok, JUnit 5, Mockito, AssertJ, Testcontainers, WireMock, Maven, Git, SVN,
Docker/Docker compose, DevOps (Spinnaker, Halyard, Helm).
● Experience with relational (PostgreSQL, MySQL, H2) and NoSQL (MongoDB) databases,
including experience in database design and PL/SQL.
● Developing RESTful Web Services and microservices as well as other kinds of backend
applications regarding various domain models.
● Experience with CI/CD, Spinnaker Pipelines, as part of the workaday DevOps routines needed
in the software development processes.
● Experience with external services such as AWS (EKS, ECS, ECR, Route 53, SES, SQS, S3,
Lambda, CodeBuild, CloudWatch), TinyPNG.
● Familiar with all phases of the software development life cycle (SDLC) including analysis,
design, development, testing, implementation and maintenance.
● Good analytical and interpersonal skills with practical experience in programming, and
problem-solving.
● Experience of working in remote and in-house teams using SCRUM, Kanban, and other Agile
methodologies.
● Master’s degree in Computer Engineering from Odessa National Polytechnic University.
● Upper-Intermediate+ English.
Skills
Languages: Java, Kotlin (base level), SQL, HTML/Javascript (base level)
Frameworks: Spring (Boot, Data, Security, Batch, Integration, MVC), Quarkus,
Vert.x, Hibernate, EclipseLink, Play, Vaadin8
Databases: PostgreSQL, MySQL, MongoDB, Oracle, H2
MoM: Kafka, ActiveMQ, RabbitMQ
Testing: JUnit, Mockito, AssertJ, Rest Assured, Awaitility, Testcontainers,
Wiremock, Gatling, k6
Build and deployment: Maven, Gradle, Docker/Docker compose, Spinnaker, Helm
CVS: Git (GitHub, GitLab, Bitbucket), SVN
External services: AWS EKS/ECS/ECR/Route53/SES/SQS/S3/Lambda/CodeBuild
/CloudWatch, TinyPNG
Monitoring: Datadog, Prometheus, Grafana, Kiali, CloudWatch
Operating Systems: MacOS, Windows, Linux
Tools: Intellij IDEA, Postman, Docker, Docker Compose, Vagrant,
SonarQube and other static analysis

Professional Experience
FNT Jan 2025 – Till now
Java Senior Engineer. Participating in the following project:

Watu
Fast, flexible and transparent financing.
Watu provides quick onboarding, flexible payments and clear terms — reliable access that works
for you over time. An ecosystem consists of multiple projects

Responsibilities:
● features implementing, bug fixing, technical investigations, documentation exploring and
enhancing
● implemented security logic with JWT and refresh tokens
● contribute to system architecture and participate in design reviews
● apply best practices in software engineering, including concurrency and performance
optimization

Used stack: Java 11/21, Spring Boot, Spring Security, Spring JDBC, Spring Scheduled, Async, JWT,
JSON Schema API, JUnit 4/5, Mockito, Awaitility, Maven; MySQL, JPA;
Jenkins, SonarQube, Bash Script, Docker, docker-compose, Git.

EPAM Oct 2020 – Dec 2025
Java Senior Engineer. Participated in the following project:
EBS-FOL - Key developer
Software Architecture and Engineering Services. Developing Open Source FOLIO Product.
Responsibilities:
● features implementing, bug fixing, technical investigations, features demonstrations
● redesigning and implementing obsolete modules with up-to-date solutions
● investigation and implementation of FIPS communication between modules and services
(Kafka, Kong, Keycloak, diverse clients)
● Troubleshooting instances and analyzing heap in ECS services
● introduced retries with exponential backoff and Circuit Breaker functionality

Used stack: Java 17/11, Vert.x, Quarkus, Spring Core, Spring Boot, Data, Spring Scheduled, Async,
AOP, Keycloak, Kong, JSON Schema API, Kafka, Micrometer, JMeter, JUnit 4/5, Mockito, Awaitility,
Gradle; Postgres, JPA;
AWS (ECS, VPC, ECR, S3, ALB, RDS, SSM, Route 53, Cloud Watch);
Jenkins, SonarQube, Terraform, Bash Script, Vagrant, Docker, docker-compose, Git.
REFI-XTHA - 8 months - Team lead
Fintech sphere. REFI-XTHA: Tick History and Time Series sub-projects.
The Time Series team is primarily focused on developing a migration solution to efficiently and
securely move Historical Data to AWS-based Cloud Solutions. This includes creating a
comprehensive strategy to integrate our current On-Premises solutions with the new AWS Cloud
Solutions. The intention is to have a smooth, quick, and secure execution of various data types via
API services.

Responsibilities:
● manage the team, technical and documentation investigation, feature development, bug fixing,
set up CI/CD, thorough code review
● managed and took part in the development of two microservices (chunk-manager,
watchlist-worker)
● set up communication between IS (ingestion-service) service with watchlist-worker via thrift
interface in AWS
● conducted knowledge transferring and demo sessions

Used stack: Java 17/11, Python, Spring Core, Spring Boot, Spring Scheduled, Spring Config, Spring
AOP, Kafka, Hadoop, Micrometer, JMeter, JUnit 4/5, Mockito, Awaitility, Gradle;
AWS (ECS, EKS, ElastiCache, Lambda, VPC, ECR, S3, ALB, NLB, Route 53, Cloud Watch);
Jenkins, SonarQube, BlackDuck, Semgrep, Twistlock, Terraform, Bash Script, Docker,
docker-compose, Git.

World-Check One - almost 2 years
Fintech sphere. World Check One (WC1) is a suite of risk intelligence applications comprising the
following capabilities to address Know-Your-Client and AML (Anti-Money Laundering).
Responsibilities:
● features implementing, bug fixing
● deep technical investigation and designing feature implementation plans
 ● covering complicated Spring Batch jobs functionality with performance tests via Gatling
● demonstration of new approaches and solutions

Used stack: Java 8, Spring Core, Spring Boot, Spring Data, Spring Security, Spring Batch, Spring
Integration, JPA, Hibernate, Flyway, Quartz Scheduler, Elasticsearch, Gatling, Rest Assured, JUnit
4/5, Mockito, Hamcrest, Awaitility, Maven;
AWS (ECS, ECR, SQS, S3, Route53, Cloud Watch, Cloud Formation);
Jira, Jenkins, Datadog, SonarQube, Git.

DIGIS Mar 2018 – Oct 2020
Java Developer. Participated in the following projects:

KekFeed v2 - 12 months
Entertainment sphere. Includes two mobile applications (iOS, Android) and REST service as
backend Back-API, Admin console.
Responsibilities - features implementing, tuning CI/CD, e.g:
● Build RESTful API
● Custom Spring Security authentication with filters and JWT
● Tuning distributed CI/CD across multiple regions to EKS cluster
● Admin console with OAuth2 SSO, frontend part in Thymeleaf and templates
● Unit test coverage

Used stack: Java 8, Spring Boot 2.3.2, Spring Data MongoDB, Spring Security OAuth2/JWT,
Mockito, MongoDB, Redis, Docker, Maven, Git, Thymeleaf, AWS(EKS, ECR, CodeBuild, S3, Lambda,
Route53, ELB), TinyPNG, Spinnaker, Helm.

EBK v2 - 5 months
Fintech sphere. Bank application. Responsibilities - development of new backend functionality, e.g:
● System monitoring of such tools like Elasticsearch, MongoDB, Hazelcast
● Authentication via OAuth2(authorization code grant) and JWT
● Unit test coverage
● Javadoc, describing technical documentation(Confluence)

Used stack: Java 8, Spring Boot 2.1, Spring Data MongoDB, Spring Security OAuth2/JWT/LDAP,
Spring AOP, Spring Data Hazelcast, Quartz Scheduler, Swagger, Elasticsearch, Apache POI,
Hazelcast, MongoDB, Mockito, Docker, Maven, Git.

Bevager - 4 months
B2B solution for optimizing costs in the restaurant and related business.
Responsibilities:
● Development of new backend functionality
● Refactoring and fixing existing components
Used stack: Java 8, Play Framework, Hibernate, MySQL, Flyway, sbt, Git.
Empower U - 5 month
Medical sphere. A CRM system for the healthcare-providing sector.
Responsibilities:
● Development of new backend functionality, modeling, analysis, architecture design
● Build REST API and service-based architectures

Used stack: Java, Spring (Boot, Core, Security, Data), MongoDB, AngularJS, Elasticsearch.

AnagraficheSmisto - 7 months
Fintech sphere. This tool is designed specifically to manage personal and fiscal information, in a
manner that is compliant with client standards. Consists of backend and frontend parts.
Responsibilities:
● Development of new backend and frontend(Vaadin) functionality
● Refactoring and fixing existing components
● Database schemas designing
● Deployment to Payara Server

Used stack: Java 8, J2EE, EclipseLink, Vaadin 8, PostgreSQL, GlassFish, SVN, Git, Payara Server.