IT graduate · developer · Geelong, VIC

I'm Callum O'Connor.Useful systems, built with care.

I build native apps, connected products and practical automation that make complicated things easier to use.

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  • SwiftUI
  • Kotlin / Compose
  • TypeScript
  • Node.js
  • Python
  • SQL
  • Git

01Selected work

The details are the work.

Two current builds, then a few projects that show how I think across code, systems and people.

01 / TapWearIn development
Product surface / 001
TapWear iPhone home screen with profile, medication and band-scanning controls.
App / home and scan
salluscloud.com
TapWear browser emergency page: verified band, Alex Morgan's fictional profile, blood type A+, allergy and emergency-contact panels.
Browser emergency page
after a band scan

Emergency information that stays close, readable and under its owner's control.

TapWear pairs emergency NFC bands and cards with a hosted profile. A scan can start with compact offline text, then open a verified profile with only the fields the owner has chosen to show.

Problem

Important details are hard to keep current when they live on a printed card or in someone else's phone.

Decision

Keep the first signal compact and offline, then use an authenticated handoff for richer, owner-controlled information.

Evidence

SwiftUI and Core NFC on iOS, Kotlin / Compose on Android, with a Node.js + SQLite backend and explicit access controls.

Built across

SwiftUI / Core NFCKotlin / ComposeNode.js / SQLite
01

Controlled access

Owner-authenticated updates, selected visible fields and band revocation.

02

Auditable sharing

Access logs, expiring one-time clinical sharing and encrypted documents.

03

Clear signals

Scan notifications and a handoff that tells the next person what to do.

Real TapWear interfaces. The browser capture demonstrates the verified-band view using a fictional emergency profile. Open either image to view it at full size.

02 / MacroLens AIPrivate personal app
MacroLens app icon.

A meal photo becomes an estimate you can actually review.

MacroLens is a private iPhone app for turning one or two meal photos into editable nutrition estimates. The app keeps the review step in the user's hands before anything is saved.

SwiftUI + SwiftDataTypeScript / ExpressOpenAI Responses APIUSDA nutrition data

Process / explicit handoff

  1. 01

    Photo

    Preprocess on request: strip metadata, compress and authenticate.

  2. 02

    Analyse

    Backend sends the request to the Responses API for structured food estimates.

  3. 03

    Review

    Every result stays editable; the user checks foods and portions before save.

  4. 04

    Save

    Reviewed foods become an editable meal record with deterministic totals.

HealthKit / Garmin energy data stays on the device. The phone bearer lives in Keychain, credentials stay on the backend and meal photos are discarded after the request.

Architecture

SwiftUI + SwiftData on iOS 18+, TypeScript / Express on the backend, with a SQLite cache and PostgreSQL deployment configuration.

Nutrition logic

USDA enrichment when configured, a local fallback, and nutrition matching with deterministic arithmetic for editable estimates.

Product surface

Today dashboard, manual entry, history, goals and CSV export support a useful loop beyond the photo request.

MacroLens is a private personal project. Photo results are estimates and are reviewed before they become saved data.

03–05Additional work

Projects that taught me to see the whole system.

These projects show range across product interfaces, integrations and systems thinking.

03

Automation + Integration

Deakin internship · Jul–Oct 2024

Built and refined Zapier / MySQL workflows, contributed across an Adalo app, and translated technical decisions for a multidisciplinary client team.

Zapier · MySQL · Adalo · technical presentations

Also created a reusable Zapier Filter Guide for recurring workflow issues.

04

VR Cycling

Unity + C# coursework

An interactive cycling project shaped around mission logic, collectables, timers and NPC racing, with feedback loops that keep the next action clear.

Unity · C# · gameplay logic · interaction design

Coursework project focused on interactive systems and feedback.

05

Cloud Native + Distributed Systems

Coursework · architecture concepts

Worked through the structures behind distributed applications: service boundaries, deployment and scaling, CI/CD, monitoring and database choices.

Microservices · deployment · CI/CD · monitoring · databases

Architecture coursework covering distributed app concepts and deployment trade-offs.

04How I work

Build the handoff, not just the feature.

The strongest work in this portfolio sits between a person and a system: a scan, a review, a next action or a piece of documentation. I care about making that boundary obvious.

01

Start with the constraint

Offline data, user consent, imperfect inputs and the people who need the next step.

02

Make the decision visible

Useful interfaces show what happened, what will happen and what the owner can change.

03

Check the edge

I look for the moments around the happy path: revocation, recovery, handoff and review.

05Background

Technical range, people-first practice.

An IT degree, engineering floor experience and client-facing work all shape how I approach software.

Jul–Oct 2024

Student Intern / Head Software and Tech Developer

Deakin University

Worked in a multidisciplinary client team across integrations, app contribution, technical documentation and presentations.

Jan–Dec 2018

Engineering Intern

Ford Australia

Calibrated dynamometers, programmed environmental chambers with real-world data, and supported test validation and troubleshooting with engineers.

Background

Client-facing support experience

People-first practice

Support work developed clear communication, patience and a habit of making the next step understandable for the person using the system.

Education

Bachelor of Information Technology

Deakin University · Mar 2020–Nov 2024

Skills with evidence behind them

Application layer

SwiftUI · Core NFC · Kotlin / Compose · C# · C++ · Python · JavaScript

Systems + data

TypeScript · Node.js · Express · SQL · SQLite · MySQL · SwiftData · PostgreSQL

Delivery + collaboration

Git · Zapier · Adalo · AWS concepts · CI/CD · technical presentations

06Contact

Let's build something that earns trust.

If you're working on a useful product, a connected system or a workflow that needs untangling, I'd like to hear about it.