John Doan

Backend Software Engineer · AI Engineer · Data Engineer · Published iOS Developer

Open for Software / AI / Data Engineer roles

Published iOS developer · App Store

Engineer building backend systems, AI-enabled apps, data workflows, live React/Angular web apps, and 16 live iOS and macOS apps — across Java, Python, Swift, and TypeScript. Every project ships with run steps, tests, and reviewable artifacts.

Projects Apps About Contact
Remote / Open to relocate john@johnvdoan.com
Portfolio • LinkedIn • GitHub

Concise resume designed for quick review. Full professional resume available upon request.

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Summary

  • Build backend services and APIs in Java and Python with clear contracts, validation, and documented endpoints (OpenAPI/Swagger).
  • Ship native iOS apps with Swift / SwiftUI — 16 apps live on the Apple App Store across education, games, finance, health, and shopping, including an Apple Watch app and on-device Apple Intelligence features. Offline-first, no tracking.
  • Build and deploy frontend web apps in TypeScript — live React 19 and Angular 22 (signals) apps on Vercel with unit-tested core logic.
  • Deliver data workflows and ETL with SQL and reproducible artifacts; comfortable with SQLite/DuckDB for local marts and rapid iteration.
  • Project work in AI/RAG: retrieval + grounding patterns and run logging to keep outputs debuggable; exploring on-device AI (Apple Intelligence / Core ML).
  • Production-minded habits: automated testing (JUnit/pytest), structured logging, Docker packaging, and CI-style checklists.

Experience

Independent Software Engineer — Self-Directed Projects
January 2023 – Present
  • Shipped 16 native iOS/macOS/watchOS apps end-to-end — design, SwiftUI/SwiftData build, App Store Connect metadata, review, and release — including CloudKit sync, an Apple Watch app, and on-device Apple Intelligence features.
  • Built and deployed eight production web apps in React 19 and Angular 22 (TypeScript) to Vercel, with unit-tested core logic (Vitest) and dependency-free SVG charting.
  • Built backend and data projects across Java and Python: API services, ETL pipelines, and analytics deliverables with reviewable outputs.
  • Packaged FastAPI scoring endpoints with tests, structured logging, Docker, and CI-style checks; wrote short runbooks (how to run + what to review).
  • Implemented Java desktop and backend patterns (service/repository layers, SQLite via JDBC, Maven builds, and JUnit basics).
  • Produced concise evaluation notes for ML work (threshold trade-offs, confusion matrix, lift/decile summaries) and documented assumptions/limitations.

Selected Projects

Java Job Application Tracker (Stages 1–5)
Java • Maven • Swing UI • SQLite/JDBC • Search/Sort • JUnit basics • Packaging
  • Staged build from console CRUD to desktop UI with SQLite persistence; added search/sort and basic tests.
Customer Metrics Pipeline & API
Python • FastAPI • ETL • Artifacts • OpenAPI
  • Built an ETL pipeline producing curated artifacts and exposed scoring via a FastAPI endpoint with Swagger/OpenAPI docs.
RAG Mini Chat (Stages 1–3)
Retrieval • Grounding • Run logging
  • Implemented staged retrieval workflows and run logs to make responses traceable and debuggable.
Support Ticket Analytics
DuckDB • ETL • Ops KPIs • Text analysis
  • Created a small DuckDB-based mart and analyzed ticket text to surface recurring operational themes and trends.
iOS, macOS & watchOS App Portfolio — 16 apps live
Swift • SwiftUI • SwiftData • watchOS • Apple Intelligence • App Store
  • Designed, built, and shipped 16 apps through App Store review — education, games, finance, health, and shopping — including CloudKit sync, an Apple Watch habit tracker, and on-device AI coaching. All offline-first, no tracking.
Live Web Apps — React & Angular
React 19 • Angular 22 • TypeScript • Signals • Vite • Vitest • Vercel
  • Eight deployed apps — including a drag-and-drop workflow board, a market-data dashboard behind an edge API-key proxy, and a signals-driven word game — all live on Vercel with unit-tested cores.

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Skills

Java Backend
Java 17+ Maven JUnit 5 JDBC SQLite Service/Repository layers
Python Backend / API
Python FastAPI Django + DRF Pydantic REST APIs OpenAPI/Swagger
Frontend / Web
TypeScript React 19 Angular 22 (Signals) Vite HTML/CSS/SCSS Vitest
iOS / watchOS
Swift SwiftUI SwiftData CloudKit Apple Intelligence App Store Connect
Data
SQL ETL DuckDB SQLite Pandas
AI / ML (project work)
RAG basics Embeddings (concepts) Evaluation/logging Classification baselines
Delivery
Docker CI checklists Git/GitHub Vercel Clear documentation Root-cause analysis Cross-team coordination

Credentials (Coursera / Credly)