# Joshua Constantine Santos > Full Stack Engineer. Serial founding engineer Location: Glendale, Arizona, United States Profile: https://flows.cv/joshuaconstantinesantos Hey there! I am a full-stack engineer, who started with programming through game development at a young age. That early passion laid the foundation for my journey into software engineering. Over the years, I've honed my skills, being able to confidently navigate complex backend systems, and crafting intuitive frontends while striking a balance between performance and aesthetics. From meticulously planning database models to developing robust APIs and crafting user-friendly interfaces, my proficiency in both backend systems and frontend development has prepared me to handle any tech challenges with finesse. If you value a blend of innovation and technical proficiency, let's connect! https://cal.com/joshua-santos Front End - Javascript (ES5, ES6+), Typescript, HTML5, CSS3, JQuery, Axios, React, React Hooks, Redux, SASS/SCSS, Webpack, Vite, Tanstack, Recoil, Jotai, Nanostores, UI/UX, Adobe Back End - NextJs, Bun, Remix, NodeJS, Express, Fastify, PostgreSQL, MySQL, MongoDB, Mongoose, Sequelize, Drizzle, NGINX, GO, Java, C# Testing/Deployment - AWS (EC2), Git, Github, Docker, DockerHub, Agile/Scrum Methodologies, Vitest, Vercel, Cloudflare, Jest, Enzyme, Mocha, Chai, React Testing Library, ClickUp, Linear, Trello, Loader.Io, K6, New Relic ## Work Experience ### Full Stack Engineer @ American Express Jan 2024 – Present | Phoenix, Arizona, United States - Strengthened production readiness by implementing pre-deployment validations, identifying and blocking misconfigured release candidates, reducing deployment risk and saving SRE and Platform teams ~5 hours per impacted release. - Led frontend modernization efforts by introducing TypeScript and scalable UI patterns, reducing complexity, enhancing accessibility, and accelerating feature delivery, while laying the foundation for long-term development stability. - Optimized search API performance, reducing query times by ~99% (1 minute to <100ms) and implemented client-side caching to significantly enhance UI responsiveness. ### Full Stack Engineer @ Kipsi Jan 2023 – Jan 2024 - Identified and resolved inefficient component composition patterns on high-traffic pages, eliminating unnecessary re-renders, improving responsiveness and boosting web vitals (performance score from ~30 to mid-70s). - Migrated heavy client-side calculations to server-side rendering with NextJS, reducing client resource usage and resolving user-reported performance issues. - Enhanced collaborative workflows by implementing a feature-rich table with search, sort, column grouping, pinning, and customizable order, along with persistent URL-driven state management, enabling teams to seamlessly share and act on dynamic data views. ### Full Stack Engineer @ SoftLedger Jan 2021 – Jan 2023 - Established engineering processes, led technical planning and sprint execution, mentored new engineers, and shaped a team culture focused on scalable growth and accelerated delivery. - Launched and scaled greenfield products through direct collaboration with customer and sales, clarifying needs, scoping MVPs, and expanding product capabilities to drive customer retention and business growth. - Scaled the platform by migrating the API gateway from Node to Go, resolving scalability bottlenecks surfaced through observability, achieving a 10x container size reduction, 90% memory usage reduction, and a 3x increase in load capacity. - Championed TypeScript adoption and developed composable internal libraries for query generation and reusable validation, accelerating feature delivery by ~99% (from 2 days to 30 minutes) and improving developer efficiency through standardized, and testable building blocks. - Redesigned backend validation and client-facing error handling to provide actionable messaging, reducing customer-reported issues by ~30% and enabling Customer Success teams to shift from reactive support to higher-value initiatives. ### Founding Engineer @ MNML Health Jan 2020 – Jan 2023 - Restructured system architecture from a monolithic service to a microservice model on Kubernetes (AWS EKS), then re-architected to a full serverless environment on Vercel with NextJS, reducing monthly infrastructure cost by 30% by aligning system complexity with product needs. - Migrated the frontend and backend applications from JavaScript to TypeScript, reducing backend code size by 65% and cutting build times by 50% (from 20 minutes to 10 minutes). - Improved backend performance by optimizing SQL queries and implementing indexing strategies, decreasing average response latency from over 800ms to 30ms (a 95% improvement). ### Software Engineer @ Open Source Jan 2021 – Jan 2021 Launched an API for accessing data quickly and securely to multiple service endpoints, while being able to handle 10 million data entries safely and consistently ### Front End Lead @ Open Source Jan 2021 – Jan 2021 Web-app that curates a list of recipes you can make that is based around what is in your pantry. ### Software Engineer @ Open Source Jan 2021 – Jan 2021 Responsible for a complete overhaul of an eCommerce frontend portal to modern standards using React and React hooks ### Expert @ Enjoy Technology, Inc. Jan 2018 – Jan 2020 | Phoenix, Arizona Area ### Sales Associate @ EXPRESS Jan 2018 – Jan 2018 | Glendale, Arizona Working sales floor to exemplify world class customer service. Exercise knowledge of promotions towards the customer to ensure daily target goal is met Organized sales floor to promote better sales. ### Seasonal Sales Associate @ Pacific Sunwear Jan 2018 – Jan 2018 | Glendale, Arizona Able to work sales floor through rush hours while staying focused and adaptive to daily target goal. Eager to represent the company's mission through customer service Negotiate customer's concerns and needs ### Barista and Cashier @ BOMBOBA LLC Jan 2015 – Jan 2016 | Tolleson Have represented the company with 5-star reviews on customer service on Yelp and Google Reviews. Worked front end to greet customers with a smile and friendly demeanor. Experience in training new staff at the cashier and making drinks. Recommended 3 exceptional workers. ## Education ### Computer Software Engineering Hack Reactor Jan 2021 – Jan 2021 ### Bachelor's degree in Computer Programming Grand Canyon University Jan 2016 – Jan 2020 ## Contact & Social - LinkedIn: https://linkedin.com/in/joshua-constantine-santos - Website: https://cal.com/joshua-santos - Website: https://www.joshsantos.me/ --- Source: https://flows.cv/joshuaconstantinesantos JSON Resume: https://flows.cv/joshuaconstantinesantos/resume.json Last updated: 2026-03-29