Aaron Hammer Email & Phone Number

New York, NY, US

San Francisco, CA, US

San Francisco, CA, US

• Engineered and led several projects for Square Payment Links on a 9-person team using Golang, PHP,Typescript, and Vue that managed over $3.5 billion in processing volume, growing 50%+ YoY for 2024.
• Drove our code red for reliability, created and owned our observability standards and our observability stack in Datadog, and wrote up a 90-day plan to that got all our SLOs from failing to 5 9s at the end of our.
• Led the migration of all our tier-1 services that manage our public Square Payment Links API as well as our internal services to AWS from on-prem infrastructure using Terraform
• Rebuilt Square Payment Link’s tipping feature to let over 1 million sellers customize tip percentages, support different currencies, and to provide more localized tipping percents as defaults.
• Cut Database load by over 98% and reduce our Public Checkout Payment API response time by an average of 70%, in come case reducing the latency from 3.6s to 85ms by auditing indexes for frequently used queries.

Washington, D.C., US

• Contributed with an 8-person Scrum team to a React front-end and Scala microservice back-end for a highly visible UHC healthcare client dashboard that’s accessed by over 50 million customers worldwide.
• Led and rapidly implemented the front-end requirements for a SSO redirect on myUHC to enable over 26 million customers to receive free COVID-19 tests by weeks end to comply with federal mandates.
• Drove a performance initiative to improve UX. I reduced our max bundle from 1.62MBs to 495KBs and slashed FCP by 0.4 seconds through lazy-loading, bundle-splitting and concurrent rendering.
• Spearheaded the front-end work for a domain unification effort on myUHC for all lines of business, resulting in a decrease in domains from 6 to 1, leading to greater customer and developer clarity.
• Contributed with a dedicated team to migrate myUHC from AngularJS to ReactJS. Removing AngularJS from our bundle led to a drop in bundle sizes by 30% and shrunk page load time by ~15%

Buffalo, NY, US

• Engineered a web and mobile React/ Expo React Native app with a Node Express backend with an Agile 5-person team for a consumer facing SaaS app.
• Reduced React bundle size ~12% with tree shaking, package pruning, and using size optimized libraries.
• Led an initiative to reduce database load and API response times by introducing a Redis cache aside strategy on top of our RESTful API Node.js backend. Cache hits approached 85% on some common endpoints.
• Modeled and created the AWS infrastructure and design docs for a scalable serverless image caching API that returns images in a specified dimension and image format while caching alternative formats. This decreased.

Buffalo, NY, US

• Participated in creating a newly published Android and iOS app created with React Native, Redux, and Expo
• Maintained and contributed to a SaaS web app built with React, Node.js, Express, Webpack, and Sass
• Developed and renovated unit tests and snapshot tests with Mocha, Chai, and Jest across both mobile and web, with an average of 92% coverage across all branches
• Engineered queries using Sequelize and raw SQL for MySQL database hosted on AWS's RDS