Payments & Fintech
REST APIs, XML, OAuth 2.0, Postman, tokenization, 3DS, Apple Pay, Google Pay, EMV, Interac, card-on-file.
TECHNICAL PORTFOLIO / LEARNING LAB
I learn systems by building them.
A growing archive of fintech, software, cloud, data, networking, and automation projects — turning coursework into working systems, documented decisions, and evidence of what I can do.
PROJECT LIBRARY
Built to prove the skill.
Every project is documented as a case study: problem, architecture, decisions, tools, challenges, results, and lessons learned.
No projects match those filters yet.
CAPABILITY MAP
What I work with.
The portfolio is intentionally broad, but the spine is systems thinking: understand the flow, isolate the failure, improve the design.
Development
JavaScript, Node.js, Python, SQL, Git/GitHub, HTML, CSS, API debugging, scripting, application logic.
Cloud & Infrastructure
AWS, Linux, PowerShell, HTTP/HTTPS, DNS, TLS/SSL, networking fundamentals, deployment workflows.
Security & Risk
PCI DSS, encryption, secure payment flows, fraud/risk systems, production readiness, QA and remediation.
Delivery & Consulting
Requirements, technical discovery, scheduling, QA coordination, developer coordination, escalations, go-live guidance.
Learning & Documentation
Technical writing, demos, training guides, case studies, project retrospectives, reusable implementation documentation.
ABOUT
Engineering foundation. Fintech experience. Builder mindset.
I’m John D., an Electrical Engineering graduate and fintech technical consultant. My day-to-day work sits between developers, payment systems, QA teams, and enterprise clients.
WrittenByD is where I make the rest of my technical development visible. Instead of collecting certificates in isolation, I use coursework as fuel for projects that can be inspected, explained, improved, and eventually reused.
The goal is simple: leave a trail of working systems behind me.