Description

Senior Backend Java Engineer available for B2B contract/freelance work through my UK limited company.

I help teams quickly deliver, fix and optimise Java/Spring Boot backend systems. My strongest areas are Spring Boot microservices, REST API development, Keycloak/OAuth2/JWT authentication, Kafka/RabbitMQ messaging, Redis caching, Docker, CI/CD and SQL performance tuning.

I am a good fit if you need help with:

- Building or fixing Spring Boot microservices

- Designing REST APIs and OpenAPI contracts

- Implementing authentication with Keycloak, OAuth2 and JWT

- Improving slow Java applications, database queries or Redis caching

- Kafka/RabbitMQ event-driven backend development

- Dockerising services and setting up CI/CD pipelines

- Short-term urgent backend support

Relevant results:

- Reduced a manual insurance process from 1 hour to 3 seconds.

- Worked on systems serving 25M+ users.

- Built Java 21/Spring Boot microservices for a SaaS product.

- Udemy instructor with 700+ students on Java, Spring Boot, Microservices, Docker and Redis.

Tech stack: Java 8–21, Spring Boot, Spring Security, Microservices, JPA/Hibernate, PostgreSQL, Oracle, MySQL, Kafka, RabbitMQ, Redis, Docker, GitHub Actions, Jenkins, Swagger/OpenAPI, JUnit.

Open to remote or on-site projects in the UK and international B2B contracts.

Industry field of expertise

Languages

English
Fluent
Turkish
Native or bilingual

Workplace preferences

Can work on-site

Sheffield (up to 50km), London (up to 50km), Birmingham (up to 50km), Cambridge (up to 50km), Oxford (up to 50km)

Ingr Technology
Java Developer (Contractor
August 2022 - September 2025 (3 years and 1 month)
United Kingdom
Designed and built domain‑driven REST APIs; contract‑first OpenAPI specifications, versioning strategy, pagination/sort/filter, request validation, and a standardised error model (problem‑details). Implemented Keycloak + OAuth2/JWT for core authentication; client‑credentials for service‑to‑service flows; secure endpoint configuration with Spring Security. Delivered core services with Spring Boot + JPA/Hibernate; added idempotency guards and retry‑safe patterns for critical operations.
Implemented Kafka-based event processing to track when users entered or left geofenced retail locations, enabling reliable, near-real-time location checks. Used RabbitMQ for reliable messaging between microservices, improving decoupling and fault tolerance in critical flows. Introduced Redis caching and async processing to remove hotspots. Set up GitHub Actions CI/CD; built Docker images and a multi‑stage pipeline (build→test→package→deploy); semantic versioning and release notes automation.
Spring boot Docker Microservices Spring Security Redis
Eleia Tech
Founder & Software Developer
September 2021 - Today (4 years and 10 months)
United Kingdom
Founded Eleia Tech, leading development and technical strategy. Designed and developed Pati (veterinary clinic system), a scalable solution using Java 21, Spring Boot, Microservices, Docker and AngularJS. Managed deployment, architecture, and optimization for seamless performance.
Spring boot Spring Security Docker Redis Microservices
Allianz
Java Developer
April 2021 - September 2021 (5 months)
Türkiye
Developed and optimized features for the Health Claim project, reducing manual processing from 1 hour to 3 seconds. Built and maintained Spring Framework services and front-ends, enhancing customer experience. Defined requirements, wrote unit tests, and validated services using Swagger. Ensured high-quality standards through code reviews and mentored junior developers.
Spring boot Java Weblogic AngularJS Oracle