Stephen Walsh

Product engineer with 10+ years experience in building iOS and full-stack applications. Currently at Kargo developing creative ad tech tools with TypeScript and Rails. I care about craft, great UX, and shipping polished products.

Experience

Software Engineer II

Kargo · Waterford, Ireland · April 2024 - Present

  • Canvas composition tool: Developed Figma-like creative canvas tool using React and TypeScript, enabling clients to create rich designs with feed data and library assets
  • Catalog preview rebuild: Rebuilt catalog preview feature from ground up with a new OpenAI-powered search feature that transforms natural language into SQL Queries
  • Asset management: Built 'My Brand' feature with Rails Controllers and AWS S3, allowing power users to upload, tag, and organize reusable assets for faster retrieval
  • AI image generation: Implemented DALL-E 3 integration with Rails backend and React frontend for on-demand high-quality image generation
  • Video automation: Worked on Dynamo mass video generation tool automating After Effects template customization for bulk video creation via CSV input
  • Legacy optimization: Optimized performance and maintainability across complex legacy Rails application, resolving bugs and improving system stability

iOS Developer Consultant

Self-Employed · Remote, Ireland · November 2018 - January 2023

  • Client app development: Delivered iOS apps for clients across US and Europe, translating concepts into functional applications
  • AR prototyping: Built ARKit prototypes collaborating with technical artists and designers to refine UX and performance
  • Architecture refactoring: Refactored entire iOS codebase to MVVM + RxSwift architecture, improving scalability and maintainability

Senior iOS Developer

Flipdish · Remote, Ireland · August 2020 - December 2021

  • Crash-free rate improvement: Increased crash-free rate from 85% to 99.98%, ensuring seamless user experience
  • Test coverage: Boosted unit test code coverage by 57%, leading to more robust and reliable code
  • Architecture refactor: Refactored entire app architecture implementing MVVM, Repository, and Coordinator Patterns to reduce systemic coupling
  • CI/CD automation: Built Fastlane pipelines automating Whitelabel app generation, App Store deployments, screenshots, and demo builds for prospective clients
  • Version management: Created Fastlane actions for tagging and versioning codebase, streamlining release process and ensuring consistency

Senior iOS Developer

Letgo · Barcelona, Spain · April 2018 - November 2018

  • Services vertical: Delivered new Services/Jobs vertical as part of cross-functional squad, resulting in 20% uplift in listings posted through bespoke feature additions
  • Technical debt reduction: Defined standardized View architecture practices and applied boy-scout rule throughout codebase, improving maintainability
  • Cross-platform subscriptions: Collaborated with backend and Android teams to design and implement cross-platform in-app subscription service
  • Test improvements: Refactored broken test cases into Quick/Nimble and increased test coverage across model layer and business logic

iOS Developer

DoneDeal.ie (Distilled) · Wexford, Ireland & Waterford, Ireland · July 2014 - April 2018

  • App Store rating improvement: Maintained 99.8% crash-free rate and contributed to increasing App Store rating from 2.0 to 4.8 stars in one year by transitioning from web-view to fully native iOS experience following Apple HIG
  • 360° capture feature: Prototyped 360° capture feature using OpenCV, enhancing product offerings for pro-user customers
  • Custom animations: Created custom tab bar icon animations using CoreAnimation (drawn completely in code) and custom save animation
  • Network layer refactor: Refactored network layer to Alamofire using the facade, improving abstraction from models and increasing modularity
  • Design system: Defined visual style guide and custom UI library with CoreGraphics, ensuring HIG compliance while maintaining brand consistency across iOS, web, and Android

Projects

Foxtrot Card Game

Multiplayer browser-based card game: Built full-stack TypeScript application with WebSockets for real-time gameplay, Docker deployment on Railway. Implemented decoupled game engine supporting multiple card game variants.

Token-Gated Writing Platform

A token-based authentication system for my creative writing portfolio. Built with Next.js and TypeScript.

Pawnomenal

iOS app using Create ML for real-time dog breed classification via device camera. Integrated OpenAI API for breed information generation. Built with SwiftUI following Apple HIG principles.


Skills

languages:
Swift | TypeScript | Ruby | JavaScript | Objective-C | HTML | CSS
frameworks:
React | Ruby on Rails | SwiftUI | UIKit | Combine | Tailwind CSS
tools:
Git | Docker | Amazon Web Services (AWS) | Fastlane | Xcode | PostgreSQL | Firebase | CI/CD
practices:
API Design | REST APIs | MVVM | Repository Pattern | Agile | Unit Testing | SOLID Principles | Full-Stack Development

Education

B.Sc. Computer Science (Entertainment Systems)

Waterford Institute of Technology · 2014

My capstone project won the 2014 Sun Life Financial Enterprise award. Placed in the semi-final for the 2014 Enterprise Ireland Student Entrepreneur of the Year Awards.