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I'm a passionate Full-stack Software Engineer with 8+ years delivering scalable Java-based solutions for enterprise-grade systems. I specialize in microservices, SQL optimization, and AWS cloud services, focusing on building resilient distributed systems, reducing latency, and improving end-to-end performance. I thrive in remote, fast-paced environments and enjoy collaborating with global teams to ship reliable software. I value clean architecture, TDD, and continuous learning to deliver high-quality results.…I'm a passionate Full-stack Software Engineer with 8+ years delivering scalable Java-based solutions for enterprise-grade systems. I specialize in microservices, SQL optimization, and AWS cloud services, focusing on building resilient distributed systems, reducing latency, and improving end-to-end performance. I thrive in remote, fast-paced environments and enjoy collaborating with global teams to ship reliable software. I value clean architecture, TDD, and continuous learning to deliver high-quality results.

John Marcel de Oliveira

Full Stack Developer, Back-End Developer, Web Developer, +2

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I'm a passionate Full-stack Software Engineer with 8+ years delivering scalable Java-based solutions for enterprise-grade systems. I specialize in microservices, SQL optimization, and AWS cloud services, focusing on building resilient distributed systems, reducing latency, and improving end-to-end performance. I thrive in remote, fast-paced environments and enjoy collaborating with global teams to ship reliable software. I value clean architecture, TDD, and continuous learning to deliver high-quality results.…I'm a passionate Full-stack Software Engineer with 8+ years delivering scalable Java-based solutions for enterprise-grade systems. I specialize in microservices, SQL optimization, and AWS cloud services, focusing on building resilient distributed systems, reducing latency, and improving end-to-end performance. I thrive in remote, fast-paced environments and enjoy collaborating with global teams to ship reliable software. I value clean architecture, TDD, and continuous learning to deliver high-quality results.

Available to hire

I’m a passionate Full-stack Software Engineer with 8+ years delivering scalable Java-based solutions for enterprise-grade systems. I specialize in microservices, SQL optimization, and AWS cloud services, focusing on building resilient distributed systems, reducing latency, and improving end-to-end performance.

I thrive in remote, fast-paced environments and enjoy collaborating with global teams to ship reliable software. I value clean architecture, TDD, and continuous learning to deliver high-quality results.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Intermediate

Language

Portuguese

Fluent

English

Advanced

Spanish; Castilian

Intermediate

Work Experience

Software Development Engineer at Fiserv (via Meta)

November 1, 2025 - Present

Building and maintaining high-performance payment microservices within Fiserv’s global financial ecosystem, with a focus on scalability, reliability, and security. Designing distributed systems using Hexagonal Architecture, DDD, event-driven design, and clean code principles. Developing resilient APIs and backend services with Spring Boot and Spring Cloud, employing circuit breakers, retries, and externalized configuration.

Senior Software Developer at Philips

October 1, 2022 - November 1, 2025

Led backend developments in healthcare domains, increasing backend test coverage by 60% with JUnit-based tests; developed a high-performance batch prescription module; refactored frontend–backend integration logic to reduce API round-trips and improve system throughput; redesigned medication visualization flow to streamline clinician workflows.

Software Developer (allocated at Philips) at AMcom

April 1, 2021 - September 1, 2022

Provided full-stack consultancy for Philips’s Tasy hospital management system, focusing on performance tuning, refactoring, and maintainability across 5+ critical healthcare modules.

Junior Software Developer at Migrate

November 1, 2020 - April 1, 2021

Developed a C++ dynamic-link library (DLL) to integrate legacy desktop systems with modern APIs, enabling cross-system data exchange and improving platform interoperability.

Junior Developer at TECNICON

June 1, 2016 - October 1, 2020

Refactored complex tax calculation modules, reducing processing runtime by 70%; optimized legacy SQL queries for rapid data retrieval; developed an internal Java-based development framework and a centralized ERP interface to improve UX and efficiency across departments.