I am Marina Haru Marcoulakis, a software engineer currently at XP Investimentos with experience across Amazon, freelance product delivery, mobile development, cloud systems, and applied AI research.
4+
years building products
850M+
records handled in large-scale data migration work
30%
manual work reduced with internal improvements
250k+
music data points used in published AI research
About
My work sits between product thinking and systems execution. I enjoy shipping interfaces that feel clear, but I am equally comfortable designing APIs, data flows, cloud infrastructure, and internal tooling.
Alongside production software, I also explore AI and cybersecurity through academic and educational projects, which keeps my engineering perspective broad and hands-on.
Experience
This section highlights recent work experience, showcasing the impact and scope of my engineering contributions across different roles.
XP Investimentos
May 2025 - Present
Building fintech products and internal tooling with a focus on reliability, payment flows, and operational efficiency.
Amazon
May 2024 - May 2025
Worked on large-scale financial services systems, combining product delivery with platform and cloud improvements.
Freelance
January 2022 - April 2024
Delivered mobile and web products end to end, from design and API integration to launch and maintenance.
Projects
This section highlights a few key projects that demonstrate the depth and impact of my work contributions.
Fintech delivery
Back-end SWE
Introduced PIX Automatico and PIX Agendado flows while helping modernize critical services and internal monitoring.
Improved payment usability, cut operational effort, and supported 99.9% uptime during service migrations.
Platform engineering
Back-end SDE
Designed and integrated an internal system that automated fiscal-data request handling for clients in Amazon's fintech expansion work.
Reduced team effort, improved service health, and supported scalable AWS-based delivery.
AI research
Researcher
Published academic work applying machine learning to song-hit prediction using a dataset of more than 25,000 music data points.
Reached roughly 70% predictive accuracy while combining data collection, modeling, and analysis.
Product engineering
Full-stack developer
Built mobile products end to end with React Native, REST APIs, and database design across both SQL and NoSQL stacks.
Delivered apps with 25% performance gains, 30% lower load times, and up to 40% faster queries.
Skills
Education
Bachelor of Computer Science
Universidade Presbiteriana Mackenzie · 2023 - in progress
Honorable mention in OBI 2023 and the XXVIII SBC Programming Marathon state finals, plus teaching assistant roles in circuits and programming.
Digital Game Programming Technician
Etec Jornalista Roberto Marinho · 2020 - 2022
Top performance in CUCo 2020, React workshop delivery, and honorable mentions in OBMEP 2021 and 2022.
Contact
I am especially interested in backend, fintech, cloud, platform, and product-focused software engineering work where reliability, scale, and thoughtful execution matter.
contato.marcoulakis@gmail.com
For full-time roles, projects, consulting, and technical conversations.
