Mobile products, built and supported in production.

React Native engineer focused on practical, high-quality mobile apps.

Six years of end-to-end ownership from architecture to store release.

Based in Nara, working with teams in Osaka and worldwide.

Ciaran Fontein

Independent products

Small products built around problems I know personally, then shipped and maintained.

KiraKiran app icon

KiraKiran

Customer and appointment management for independent nail salons.

iOS · React Native · Expo
Meigaza application icon

Meigaza

A shared movie queue that helps friend groups decide what to watch.

iOS · React Native · Expo
Fate app icon

Fate

A quick, fair way for groups to choose an order, teams, or a winner.

iOS · React Native · Expo

Mobile QA with Maestro

Reliable staging coverage for real iOS and Android flows.

Built a staging-locked Maestro and YAML black-box harness covering smoke, adversarial, CRUD, restart, public-booking, and Stripe card PaymentSheet flows. Added stable selectors, safety guards, JUnit reports, screenshots, cleanup, and device targeting. Cross-role messaging was designed and instrumented as a coordinated two-device protocol.

Recommendation

From Guusto engineering leadership

“He demonstrated strong technical independence, handling feature development, releases, production issues, and the day-to-day challenges of maintaining a mobile application in production.”

Felipe Santos da Rocha, Director of Software Engineering at Guusto

Production ownership

I joined Guusto when the company had seven employees. Before a product team was hired, I often decided what needed attention next. Later I worked from Figma designs and Jira tickets with product, design, backend, and web teams.

Built and shipped

  • Designed the React Native and TypeScript app architecture and built the mobile app from scratch.
  • Integrated REST and GraphQL-backed data, native services, push notifications, authentication, wallets, and recognition flows.
  • Handled certificates, store submissions, review rejections, version upgrades, performance work, and production incidents.

Worked with people

  • Reviewed designs throughout six years at Guusto and reviewed teammates' code during the final six months.
  • Debugged mobile problems with React Native, backend, and web engineers across time zones.
  • Documented the app and trained the successor team during a three-month technical handover.
Guusto search and recognition options on mobileGuusto flexible reward redemption optionsGuusto mobile wallet for received giftsGuusto charity donation impact screenGuusto non-monetary employee recognitionGuusto recognition reporting dashboard

Selected products

Each product began with a problem I wanted to solve.

KiraKiran

Customer and appointment management for independent nail salons.

Japanese-first React Native and Expo app with calendars, client history, reference photos, Supabase row-level security, and a staging-locked Maestro QA harness.

Meigaza

A shared movie queue that helps friend groups decide what to watch.

One Expo codebase for iOS and web, with Japanese and English localization, team scoring, TMDB and iTunes search, and Supabase persistence.

Fate

A quick, fair way for groups to choose an order, teams, or a winner.

React Native, Expo, TypeScript, and Reanimated. Supports 2 to 32 players, balanced teams, elimination rounds, undo, and reduced motion.

Experience

Mobile product work is the centre of my experience, supported by earlier web and game development.

  1. Guusto Gifts Inc.

    Frontend Engineer, contract and remote

    Sole React Native developer for the production iOS and Android app. Owned architecture, feature delivery, releases, incident response, performance work, reviews, and final technical handover.

  2. Independent game development

    Unity and C# developer

    Built strategy, simulation, puzzle, RPG, and action prototypes for mobile, web, and desktop.

Education

  • RED AcademyFull Stack Development bootcamp
  • British Columbia Institute of TechnologyGame Development coursework
  • British Columbia Institute of TechnologyComputer Information Technology

Skills

My strongest skills come from building, releasing, and supporting mobile apps.

Mobile product engineering

  • React Native
  • Expo
  • TypeScript
  • JavaScript
  • React
  • Responsive mobile UI
  • Accessibility and testID selectors

Production ownership

  • iOS and Android releases
  • App Store and Google Play review
  • Native integrations
  • Push notifications
  • Deep links
  • Performance and crash triage
  • On-call incident response

Quality and testing

  • Maestro
  • YAML
  • Mobile end-to-end testing
  • Black-box and adversarial testing
  • Regression and smoke testing
  • JUnit reporting
  • Synthetic test data
  • Release QA

Platform and collaboration

  • REST
  • GraphQL
  • Node.js tooling
  • Supabase
  • Git and Bitbucket
  • Docker locally
  • Jira
  • Code and design reviews
  • Cross-team debugging

What colleagues say

“He played a foundational role in building the mobile app from the ground up, and his contributions have shaped the product in a lasting way.”

Sarah Tong, Senior Product Designer and Web Developer at Guusto

“He's not only a talented mobile engineer but also someone who's incredibly communicative, thoughtful, and easy to work with.”

Sreeja Guttula, Product Manager at Guusto

Contact

I am looking for React Native and mobile product roles in Osaka, elsewhere in Japan, or remote.