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Hi there! I'm Mehmet Karaoğlu, a Senior Java Engineer with 8+ years of experience architecting fault-tolerant, distributed systems for Fortune 500 clients such as Sainsbury's and Nordstrom. I specialize in Spring Boot, Kafka, and AWS, delivering scalable platforms that handle millions of events daily while cutting infrastructure costs. I thrive in remote contract roles, leading microservices migrations and implementing AI-powered testing to boost quality and uptime. I'm passionate about domain-driven design, event-driven architectures, and building resilient integrations across complex ecosystems. I enjoy collaborating with cross-functional teams, mentoring developers, and delivering reliable software at scale. I continuously seek opportunities to optimize performance, reduce costs, and improve engineering processes with a focus on maintainability and quality.…Hi there! I'm Mehmet Karaoğlu, a Senior Java Engineer with 8+ years of experience architecting fault-tolerant, distributed systems for Fortune 500 clients such as Sainsbury's and Nordstrom. I specialize in Spring Boot, Kafka, and AWS, delivering scalable platforms that handle millions of events daily while cutting infrastructure costs. I thrive in remote contract roles, leading microservices migrations and implementing AI-powered testing to boost quality and uptime. I'm passionate about domain-driven design, event-driven architectures, and building resilient integrations across complex ecosystems. I enjoy collaborating with cross-functional teams, mentoring developers, and delivering reliable software at scale. I continuously seek opportunities to optimize performance, reduce costs, and improve engineering processes with a focus on maintainability and quality.

Mehmet Karaoğlu

Programmer, Back-End Developer, Cloud Developer, +3

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Hi there! I'm Mehmet Karaoğlu, a Senior Java Engineer with 8+ years of experience architecting fault-tolerant, distributed systems for Fortune 500 clients such as Sainsbury's and Nordstrom. I specialize in Spring Boot, Kafka, and AWS, delivering scalable platforms that handle millions of events daily while cutting infrastructure costs. I thrive in remote contract roles, leading microservices migrations and implementing AI-powered testing to boost quality and uptime. I'm passionate about domain-driven design, event-driven architectures, and building resilient integrations across complex ecosystems. I enjoy collaborating with cross-functional teams, mentoring developers, and delivering reliable software at scale. I continuously seek opportunities to optimize performance, reduce costs, and improve engineering processes with a focus on maintainability and quality.…Hi there! I'm Mehmet Karaoğlu, a Senior Java Engineer with 8+ years of experience architecting fault-tolerant, distributed systems for Fortune 500 clients such as Sainsbury's and Nordstrom. I specialize in Spring Boot, Kafka, and AWS, delivering scalable platforms that handle millions of events daily while cutting infrastructure costs. I thrive in remote contract roles, leading microservices migrations and implementing AI-powered testing to boost quality and uptime. I'm passionate about domain-driven design, event-driven architectures, and building resilient integrations across complex ecosystems. I enjoy collaborating with cross-functional teams, mentoring developers, and delivering reliable software at scale. I continuously seek opportunities to optimize performance, reduce costs, and improve engineering processes with a focus on maintainability and quality.

Available to hire

Hi there! I’m Mehmet Karaoğlu, a Senior Java Engineer with 8+ years of experience architecting fault-tolerant, distributed systems for Fortune 500 clients such as Sainsbury’s and Nordstrom. I specialize in Spring Boot, Kafka, and AWS, delivering scalable platforms that handle millions of events daily while cutting infrastructure costs. I thrive in remote contract roles, leading microservices migrations and implementing AI-powered testing to boost quality and uptime. I’m passionate about domain-driven design, event-driven architectures, and building resilient integrations across complex ecosystems.

I enjoy collaborating with cross-functional teams, mentoring developers, and delivering reliable software at scale. I continuously seek opportunities to optimize performance, reduce costs, and improve engineering processes with a focus on maintainability and quality.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Language

English

Fluent

Turkish

Fluent

Work Experience

Senior Java Engineer (Contract) at Sainsbury's

July 1, 2025 - October 29, 2025

Led the Food eCommerce Transformation initiative by building a microservices-based basket and checkout platform using Java 21, Spring Boot 3.5.6, and MongoDB. Implemented OAuth 2.0/JWT, observability with Prometheus, Grafana, and OpenSearch, achieving 99.9% availability for 50K+ daily transactions. Reduced incident detection from 15 minutes to 2 minutes, preventing ~30% of production issues. Introduced mutation testing with Pitest (90%+ mutation score) to boost CI quality. Implemented a MongoDB TTL data-cleanup strategy reducing storage costs by 30% and integrated 6 critical systems via domain-oriented microservices, trimming boilerplate by 40%.

Senior Java Engineer (Contract) at Nordstrom

June 1, 2025 - June 1, 2025

Engineered core components of an enterprise payment platform, building its event-driven infrastructure and an AI-powered test automation framework. Scaled the platform to process 900K+ daily events using Apache Kafka and serverless AWS Lambda. Reduced QA effort by 60% and prevented 15+ annual defects with LangChain4j-based test generation. Eliminated duplicate payments through fault-tolerant, exactly-once processing. Improved data integration reliability by 40% via a reusable data mapper for 20+ JSON-to-DynamoDB transformations.

Lead Engineer (Contract) at Streamlyne

April 1, 2024 - April 1, 2024

Architected migration of a 1M+ LOC monolith to a distributed microservices architecture on AWS, modernizing a platform used by 5,000+ university researchers. Defined migration roadmap with Domain-Driven Design and the Strangler Fig pattern for zero-downtime transition. Mentored a team of 5 developers, delivering 90+ AWS Lambda functions, and maintained 99.8% platform uptime during the migration. Achieved $120K annual infrastructure cost savings by adopting a cost-effective serverless architecture.

Freelance Software Developer at Self-Employed

October 1, 2022 - October 1, 2022

Delivered 6 custom Java/Spring Boot applications for e-commerce clients, managing full development lifecycles from requirements analysis to production deployment. Designed RESTful APIs, database schemas (MySQL/MongoDB), and business logic for inventory management, order processing, and customer management. Maintained an 80% client retention rate through reliable delivery, code quality, and ongoing technical support.