Juan Sepulveda

Senior Full Stack Engineer

JS

About

Senior Full Stack Engineer with 13+ years building products end to end across mobile, web, and backend.

I obsess over two things: the experience users get and the experience developers have building it. That means shipping features that deliver real value to customers, while investing in testing, automation, and tooling so the team can move fast and ship safely. Most recently in consumer fintech.

Specialized in TypeScript, React / React Native, Node.js, and GraphQL.

Experience

Arro Finance

Senior Full Stack Engineer

Nov 2024 - Mar 2026

I owned a lot of the mobile app (React Native/Expo) and worked across the NestJS backend too. My most recent project was Credit Builder, which hit $45K+ MRR in just two months.

Led the migration from Apollo/GraphQL to REST with TanStack Query and Zustand, and introduced a service and viewmodel architecture to pull business logic out of components.

I built a backend-driven UI system so we could control components, features, and copy from the server without pushing OTAs. On the backend I designed an event-driven architecture so modules could react to things like payments and onboarding without being coupled to each other.

When I joined there were no tests; I added coverage for everything I shipped, including E2E for web onboarding. I also automated the app release pipeline (OTAs, App Store) so we could ship as many times as we wanted in the week.

TypeScript
React Native
Expo
NestJS
GraphQL
PostgreSQL
Redis
AWS CDK
Docker
Go
Python
Plaid
Stripe
Tailwind

Easyapps

Senior Software Engineer

Sep 2021 - Jan 2024

I built custom enterprise apps on top of Airtable and monday.com, set up code standards for the team, and mentored junior devs weekly.

My biggest project was a resource allocation app for Riot Games' marketing department. It helped them optimize how they assigned talent, cut down on vendor costs, and saved them hundreds of thousands of dollars a year. I also built connectors to export Airtable data into Tableau and Databricks so they could measure ROI per campaign.

Typescript/Javascript
ReactJS
NextJS
Firebase
Python 3
Tableau
Databricks

We Make Websites

Frontend Developer

Nov 2020 - Oct 2022

I built and maintained Shopify storefronts for big-name clients like BBC and Hasbro. The work was mostly frontend: building features, fixing bugs, improving performance and accessibility, and rebuilding components to make the stores better. Worked closely with designers, PMs, and other frontend devs to ship on time.

Javascript
Shopify
Liquid
VueJS
ReactJS

DIGITAL ENHANCEMENTS, L.L.C.

Software Engineer

Jul 2016 - Nov 2020

Led design and architecture decisions. Designed testing strategies and implemented CI/CD workflows. Created GraphQL APIs, built APIs for mobile applications, and developed a marketplace with Stripe for payments and financial services. Implemented a highly personalized permissions system.

Typescript/Javascript
Python 3
Django
GraphQL
RESTAPI
Angular 2+ to 10
Stripe
Keycloak
Docker
Kubernetes
Postgres
Rancher
Google Cloud

VIXICOM, LLC

Software Developer

Nov 2012 - Jul 2013

Built the INTRANET of the company for managing internal processes such as the hiring process, payments, support tickets, and project management. Automated the process of creating scripts for handling inbound calls.

PHP
Javascript
HTML
CSS
Java
Mysql

Skills

TypeScript/JavaScript
Python
React / React Native
Expo
Next.js
NestJS
Node.js
GraphQL
REST
TanStack Query
Zustand
PostgreSQL
Redis
AWS
Tailwind
Stripe
Plaid
CI/CD
TDD

Education

Las Americas Institute of Technology

Technologist in Software Development

2010 - 2012