Aaron Hammer

Full Stack Developer, Side Project Enthusiast, and API Consumer

Blog

Date

Title

October 2022 - Present

Full Stack Software Engineer L4

Designed and led several projects for Square Payment Links on a 9-person team using Golang, PHP, Typescript, and Vue that managed over $2.2 billion in processing volume, growing 54% YoY for 2023.
Rebuilt Square Payment Link’s tipping feature to let over 1 million sellers customize tip percentages, support their local currencies, and to provide more localized tipping percents as defaults.
Created new observability standards by migrating the team’s observability stack to Datadog, introducing anomaly alerts, better monitoring dashboards, front-end metric alerting, and automatic API acceptance testing.
Led the migration of all tier-1 services that manage public Square Payment Links’ API and our other internal services and databases from on-prem to AWS infrastructure using Terraform.
Created the buyer-side flow for Square’s restaurant QR code checkout experience, bringing over $70 million in processing volume for Square Payment Links’ MoM.

July 2021 - October 2022

Full Stack Software Engineer II

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%

August 2019 - July 2021

Full Stack Software Developer

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 library
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 total image requests transfer size on some pages by over 80%.

May 2018 - August 2019

Intern

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

October 2023 - Present

- Owner and Creator

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

January 2023 - October 2023

- Owner and Creator

Service that lets users share costs with friends and family with one-time and subscription payments. Built with React Server Components, TailwindCSS, MySQL, and Stripe for payment processing.