Tymofii S.-Senior Java Developer / Architect
Check rate
Experience
Senior Backend Developer
Medavis
- Developed backend features for Modern RIS, a web-based Radiology Information System integrated with the existing Classic RIS via WebView.
- Worked on a modular Spring Boot backend covering clinical workflows such as appointments, examinations, patients, orders, reporting, billing, and inventory.
- Contributed to event-driven architecture using domain events to decouple workflows across backend modules.
- Implemented REST/OpenAPI endpoints, service-layer business logic, DTO mapping, validation, and integration points for the React frontend.
- Worked with PostgreSQL-backed domain models, Liquibase database changes, read/write model separation, and legacy RIS database structures.
- Integrated authentication and authorization flows using Keycloak and OAuth2.
- Added and maintained unit/integration tests using JUnit, Rest Assured, Testcontainers, and project-specific test utilities.
- Supported CI/CD and local development workflows using Maven, Docker Compose, Jenkins, and generated OpenAPI clients.
Tech stack: Java 21, Spring Boot 3.5, Maven, PostgreSQL, Liquibase, Keycloak, OAuth2, REST, OpenAPI/Springdoc, MapStruct, Lombok, Docker, Testcontainers, Jenkins.
Fullstack Java Developer
Ratepay
- Design and Implementation of solution to integrate with external bank API to issue loan contract for a purchase
- Integration into existing high rate application
- Created a spring boot service that is exposed publicly, validates and performs data exchange with external banking API
- Created UI for customers who are requesting a credit card for a purchase
Tech stack: Kotlin, Java 17, Spring Family frameworks, maven, Postgres, Flyway, Kafka, REST, OAuth, AWS ECS, AWS Coded Pipeline, ReactJs, Typescript
Senior Backend Developer / Architect
Cubic
- Design and Implementation of transportation software: ticket purchase, issue and payment
- Payment integration with banks and payment gateways (Ebics, DirectPOS)
- Booking system design and implementation
- Data migration
Tech stack: Kotlin, Java 17, Spring Family frameworks, maven, Ansible, docker, MySql, Postgres, Liquibase, REST, JWT, IAM, Jenkins, Github Actions
Senior Java Developer
Davaso
- Healthtech: handling healthcare prescriptions
- Drools business rules development: every rule resulted to a conclusion whether to payout issued prescription or not
- Business rules engine development and support
Tech stack: Java 17, Spring Family frameworks, maven, Drools, REST, Gitlab
Senior Java Developer / Architect
Modirum
- Software design and implementation of 3-D Secure payment protocols
- Created a spring boot based distributed solution for processing, handling and distribution of large amount of data: card ranges coming from Visa, MasterCard, AMEX, etc
- Architectural solution for self-hosted and client-hosted setups including k8s-based platforms
- Setup of development, release and delivery processes from scratch
- Converting SOAP API into Restful Services, Building middleware services that adapts SOAP API to REST
- Created UI for
Tech stack: Kotlin, Java 8, 11, 17, Spring Family frameworks, maven, ant, AWS, Azure, Kubernetes, Prometheus, Tomcat, docker, MySql, MongoDB, Liquibase, gGRC, REST, JWT, IAM, Jenkins, Github Actions, ReactJs, Typescript
Senior Java Developer
Targens / MySaveID
- Implemented service-based architecture using Spring family stack
- Integration with blockchain networks: Ethereum, Corda and Indy. Setup of blockchain network on Kubernetes infrastructure.
- JWT based authentication with Keycloak and Spring
Tech stack: Java 17, Spring Family frameworks, Postgres, maven, Liquibase, Azure, Microservices, Kubernetes, helm, docker, prometheus, R3 Corda, Indy, Etherium, REST, JWT, IAM
Full-Stack Developer in Test
Aura Labs
- Playing a full-stack developer role in a very dynamic start-up.
- StartUp is about creating a recruitment network of developers all over the world and creating a coin which may become a payment method for this
- Setting up kubernetes google cloud based infrastructure from scratch
Tech stack: NodeJs, Vue, MongoDB, Redis, Kubernetes
Full Stack Java Developer
Tipico
Implemented both user facing and backend software for Tipico Shops
Developed user registration flow including full KYC and integration with Signotec signature pad
Built legal tracking and reporting system to retrieve customer details about any customer entering shop
Integrated face2face and TOTP based payment solutions for retail
Integrated customer-facing applications with external payment providers like Paypal, Neteller, Wirecard for online customers
Implemented KYC and AML requirements
OAuth2 server side implementation
Authentication and authorisation implementation following OAuth2 standard using authorization code, client_credentials, password flows across microservice and user facing applications
Full cycle software development: architectural design, prototyping, scaling, high availability and monitoring
Implemented 2k+ requests/sec service with 2-4ms latency for 99% of requests
Developed sanity check ReactJS/Spring based application for a 100+ service/legacy stack
Introduced a new Software Developer in Test role for the entire company and improved scrum teams quality assurance and end-to-end responsibility
Coached developers in unit/integration testing and TDD
Java development as team member and continuous delivery
Performance critical design and testing
Test automation following Test Pyramid approach
Tech stack: Java 6, 8, 12, Spring Family frameworks, maven, python, Aws, Microservices, kubernetes, helm, prometheus, redis and elasticache, MongoDB, mariadb, kafka, AWS (S3, lambda, cloudwatch, IAM), JSON based Api, swagger, Reactive WebClient API, ReactJS, TypeScript
Java Developer in Test
Traveltainment (via Amadeus Ukraine)
Organized and implemented testing at all application layers
Implemented test based continuous integration
Performed bug fixing
Converting SOAP API into Restful Services
Tech stack: Java 8, Mysql, Wildfly, Weld CDI
Java Developer
Kuoni DestinationManagement (via Ciklum)
Designed, developed and tested software following standard software development processes
Developed and unit tested applications
Tech stack: Java 6,8, Oracle DB, Spring 3 and 4, Hibernate, ActiveMQ, Liquibase
Senior Test Automation Engineer
Kuoni DestinationManagement (via Ciklum)
Pair programmed with developers
Designed tests and software
Automated tests and reviewed code
Conducted performance testing
Senior Test Automation Engineer
Redcats (via Ciklum)
- Created, integrated and maintained an automation test framework
- Test automation patterns: Page Object, DSL
QA / Business Analyst
N2V (via Ciklum)
Managed full-cycle quality assurance
Defined acceptance criteria
Managed release, deployment and demos
Administered test/staging/prod environments
QA / Test Manager
IOIX-Ukraine
Managed a testers team (4 members)
Conducted technical interviews for tester positions
Developed test plans and test suites
Reviewed test cases
QA
Soft-Ukraine
- Developed and executed test cases
Industry experience
See where this freelancer has spent most of their professional time.
Experienced in Information Technology, Sport, Tourism, Healthcare, Banking and Finance, and Transportation.
Business area experience
See which departments and functions this freelancer has contributed to most.
Experienced in Information Technology, Quality Assurance, Product Development, and Legal.
Summary
Senior Full Stack Java Developer with 18+ years of experience designing and delivering enterprise applications across fintech, healthcare, transportation, and identity management. Strong expertise in Java, Kotlin, Spring Boot, React, cloud-native technologies, and secure distributed systems. Proven track record of building scalable, high-performance solutions while contributing across architecture, backend, frontend, and DevOps.
Skills
- Backend: Java (6–23), Kotlin, Python, J2ee (Ejb, Jpa), Spring Boot, Spring Framework, Spring Mvc, Spring Security, Spring Data (Jpa, Jdbc), Spring Cloud, Spring Reactive, Spring Cache, Spring Rest Docs, Tomcat, Jboss, Netty, Jobrunr
- Databases & Messaging: Postgresql, Mysql, Mariadb, Ms Sql Server, Mongodb, Redis, Kafka, Hibernate, Liquibase, Flyway
- Apis & Integration: Rest, Http, Grpc, Openapi/Swagger, Protobuf, Json, Xml, Soap
- Build Tools: Maven, Ant
- Cloud & Infrastructure: Aws, Azure, Google Cloud, Kubernetes, Helm, Docker, Terraform/Terragrunt, Prometheus, Hashicorp Vault
- Cloud Services: Aws Lambda, Sqs, Elasticcache, Aurora, Secrets Manager, Iam, Cloudwatch, S3, Ec2, Azure Kubernetes Service (Aks), Azure Container Registry, Azure Database For Postgresql, Azure Database For Mysql
- Identity & Access Management: Oauth 2.0, Openid Connect (Oidc), Keycloak, Spring Security, Jwt, Rbac, Authorization Code Flow, Client Credentials Flow, Password Flow, Service-To-Service Authentication, Token Validation, Tls/Mtls, Aws Iam, Aws Secrets Manager, Hashicorp Vault
- Architecture: Microservices, Monoliths, Event-Driven Architecture, Hexagonal Architecture, Domain-Driven Design (Ddd), Dynamic Scaling, Uml
- Ci/Cd & Devops: Github Actions, Gitlab Ci, Jenkins, Bitbucket Pipelines
- Frontend: React, Vue.Js, Typescript, Javascript, Html, Css
- Blockchain: R3 Corda, Hyperledger Indy, Ethereum
- Testing: Junit, Spring Boot Test, Mockito, Assertj, Wiremock, Restassured, Testcontainers
- Agile: Scrum, Kanban
Languages
Education
Oles Honchar Dnipro National University
Master degree in Engineering Physics · Engineering Physics · Dnipro, Ukraine
Statistics
Experience
Global experience
Expertise
Qualifications
Profile
Frequently asked questions
Have questions? Find more information here.
Tymofii is based in Karlsruhe, Germany and prefers 100% remote projects.
Tymofii speaks the following languages: Ukrainian (Native), German (Advanced), English (Advanced).
Tymofii has at least 20 years of experience. During this time, Tymofii has worked in at least 13 different roles and for 14 different companies. The average length of individual experience is 1 year and 4 months. Note that Tymofii may not have shared all experience and actually has more experience.
Based on recent experience, Tymofii would be well-suited for roles such as: Senior Backend Developer, Fullstack Java Developer, Senior Backend Developer / Architect.
Tymofii's most recent position is Senior Backend Developer at Medavis.
In recent years, Tymofii has worked for Medavis, Ratepay, Cubic, Davaso, and Modirum.
Tymofii is most experienced in industries like Information Technology, Sport, and Tourism. Tymofii also has some experience in Healthcare, Banking and Finance, and Transportation.
Tymofii is most experienced in business areas like Information Technology, Quality Assurance, and Product Development. Tymofii also has some experience in Legal.
Tymofii has recently worked in industries like Information Technology, Healthcare, and Banking and Finance.
Tymofii has recently worked in business areas like Information Technology and Product Development.
Tymofii holds a Master in Engineering Physics from Oles Honchar Dnipro National University.
Tymofii is immediately available full-time for suitable projects.
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Calculated based on our freelancers’ daily rates as of 7 Sep 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
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