AARON HAMMER

Senior Full Stack Software Engineer

Full Stack Software Engineer

• Designed and led several projects for Square Payment Links on a 9-person team using Golang, PHP, TypeScript, and Vue that managed over $4.1B in processing volume, growing 54% YoY for 2024.
• Rebuilt Square Payment Links' tipping feature enabling over 1M+ sellers to customize tip percentages in their local currencies, with localized defaults.
• Created new observability standards by migrating the team's stack to Datadog, introducing anomaly alerts, enhanced dashboards, front-end metric alerting, and automatic API acceptance testing.
• Led the migration of all tier-1 services for Square Payment Links from on-prem to AWS using Terraform.
• Built the buyer-side flow for Square's restaurant QR code checkout experience, contributing ~$70M in monthly processing volume.

Full Stack Software Engineer

• Contributed with an 8-person team to a React front-end and Scala microservice back-end for a UHC dashboard accessed by 50M+ members.
• Implemented urgent SSO redirect on myUHC enabling 26M customers to order free COVID-19 tests in compliance with federal mandate within one week.
• Drove performance initiative cutting the max bundle from 1.62 MB to 495 KB and reducing FCP by 0.4 s via lazy-loading and bundle splitting.
• Spearheaded front-end domain unification reducing domains from 6 to 1 for improved UX and developer clarity.
• Migrated myUHC from AngularJS to ReactJS, shrinking bundle size by 30 % and page-load time by ~15 %.

Junior Full Stack Software Engineer

• Engineered a web and mobile React / Expo React Native app backed by Node Express in a 5-person Agile team.
• Reduced React bundle size ~12 % with tree-shaking and package pruning.
• Introduced Redis cache-aside strategy, achieving ~85 % cache-hit rate on common endpoints and lowering DB load.
• Designed serverless image-caching API on AWS, cutting image transfer size by 80 % on heavy pages.

Software Engineering Intern

• Helped build newly released Android & iOS app using React Native, Redux, and Expo.
• Maintained SaaS web app built with React, Node.js, Express, Webpack, and Sass.
• Added unit & snapshot tests with Mocha, Chai, and Jest achieving ~92 % coverage.
• Wrote optimized SQL and Sequelize queries for MySQL database on AWS RDS.

• Helps users find the best deals on video games across multiple stores. Built with Solid.js, TailwindCSS, and Golang.

• Service enabling friends and family to share costs through one-time or subscription payments. Built with React Server Components, TailwindCSS, MySQL, and Stripe.

Bachelor of Science in Computer Science