Leon Haggarty
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Frontend Developer

Leon Haggarty

Diligent problem solver with strong oral and written communication, a winning attitude, and experience across startup, corporate, and agency environments.

Greater Toronto AreaPortfolioEmailLinkedin

Highlights

  • Diligent problem solver
  • Strong communicator
  • Winning attitude
  • Corporate & startup experience

Work Experience

Current

Senior Software Engineer (Retail Staking & DeFi Lend)

Coinbase·Toronto, ON

Sept 2024 – Present

  • Frontend DRI for Instant Unstaking: shipped a new liquidity flow with rollout safety, dogfooding, production validation, and resilient UX for failure modes.
  • Founding frontend engineer for Coinbase Lend MVP: delivered core product surfaces and flows plus a scalable foundation for eligibility/content configuration and analytics hooks.
  • Improved reliability and observability across staking by tightening error handling and upgrading monitoring practices to reduce noisy failures.
  • Shipped staking UX and growth surfaces (input wheel, eligibility CTAs, regional launch support, purchase-flow integrations) to reduce user confusion across entry points.
  • Authored technical design docs and runbooks; partnered with backend, product, design, and data on API contracts, edge cases, sequencing, and rollout criteria.
Current

Creator & Solo Developer

Pro Hockey Sim·Side Project

Nov 2024 – Present

  • Shipped a cross-platform NHL game simulation app (React Native/Expo, Next.js API, React web) end-to-end, from engine to App Store listings, averaging ~15 downloads/week.
  • Engineered client-side simulation with API fallback, batch runs, and pre-simulation for instant win probabilities; integrated live NHL data and real betting odds.
  • Built AI-powered summaries (OpenRouter/GROQ/Gemini), managed player ratings via Contentful CMS, and tracked analytics with MongoDB Atlas.
  • Published to Apple App Store and Google Play via EAS Build; shipped an SEO-optimized marketing site with deep linking and feature flags.

Senior Software Engineer (Growth Foundations)

Coinbase·Toronto, ON

Apr 2021 – Sept 2024

  • Built and evolved an internal no-code communications platform: led a multi-quarter redesign, improved authoring UX and validation, and removed legacy code.
  • Engineered and optimized the logged-out website: developed reusable templates and URL mapping for product and marketing pages.
  • Shipped features across the logged-in React web app and React Native mobile apps, including user preferences, growth surfaces, and cross-platform parity improvements.
  • Led frontend execution by writing design docs, running cross-functional coordination, reviewing PRs, and driving production-quality standards.

Lead Frontend Developer, Developer II

Loblaw Digital·Toronto, ON

Nov 2019 – Jun 2021

  • Shipped customer-facing features for high-traffic e-commerce web apps across Loblaw-owned retail brands.
  • Led marketplace integration work to support 3rd-party vendor products and fulfillment flows behind feature flags.
  • Drove a migration to Contentful CMS and introduced reusable UI patterns to accelerate content updates.
  • Scoped epics, wrote task breakdowns, defined data models, and maintained quality via PR reviews and build/test tooling.

Senior Frontend Developer, Frontend Developer

Giftagram·Toronto, ON

Feb 2018 – Nov 2019

  • Built features across consumer web, corporate gifting web, internal/admin portals, and a React Native kiosk app.
  • Coordinated delivery by translating requirements into scoped work and partnering with backend and mobile engineers.
  • Standardized API request/response patterns and improved release quality via QA, debugging, and validation.
  • Produced interactive prototypes and demos for enterprise pitches; partnered with design/PM to keep UX consistent.

Full Stack Developer

RC Design·Newmarket, ON

May 2016 – Feb 2018

  • Delivered end-to-end client websites and web apps, including occasional mobile work.
  • Built responsive, SEO-friendly experiences with accessibility requirements (AODA).
  • Owned DNS management, server configuration, SSL setup, and environment troubleshooting.
  • Raised quality via QA, debugging, and lightweight unit testing across multiple client projects.

Full Stack Developer

DEMHUB·Toronto, ON

Aug 2015 – Apr 2016

  • Built product features for an emergency responders networking and learning platform.
  • Partnered with the CTO on roadmap planning and iterative releases.
  • Worked across a full-stack web environment (PHP Laravel/MySQL, JavaScript/React) with basic monitoring and deployment workflows.

Stack Experience

Frontend

TypeScript/JavaScript8 yrs
React7 yrs
Next.js4 yrs
Vue/Nuxt3 yrs

Mobile

React Native4 yrs
Expo2 yrs
App Store Publishing1 yrs

API & Backend

Node.js7 yrs
GraphQL/Relay4 yrs
PHP/Laravel4 yrs
Python2 yrs
Golang1 yrs

CMS & Content

Contentful4 yrs

Styling & UI

React Native styles6 yrs
React Query3 yrs
Styled Components3 yrs
MUI / Zod / RHF2 yrs

Testing

Jest4 yrs
E2E Testing2 yrs

Infrastructure

Vercel/Netlify4 yrs
AWS2 yrs
CI/CD1.5 yrs
Akamai1 yrs

AI & Automation

MCP1 yrs
AI Agents1 yrs
Automation Flows1 yrs

Skills & Tools

📊

Observability & Monitoring

DatadogSentryBugsnagSupersetAmplitude
🗄️

Data & Databases

SQLMongoDBGoogle Firebase
📋

Project Management

JiraLinearAsanaClickUpPivotal Tracker
⚡

Ops & Automation

Slack workflowsSlack appsAmazon SESS3Lambda
🛠️

Developer Tooling

GitLabViteWebpackBrowserStack
🤖

AI Tools

CursorClaude CodeLibrechatOpenRouterGroq

Education

🎓

Master of Digital Media

Ryerson University

📚

Bachelor of Applied Management in E-Commerce

University of New Brunswick

🎬

Diploma in Film Production

Confederation College