Garrin Costa, Jr.'s Work | ContraWork by Garrin Costa, Jr.Garrin Costa, Jr.
Full-stack software developer, AI engineer, music producer
GLLRST is an art-collecting app where users search the Harvard Art Museums and Art Institute of Chicago APIs, build a gallery, trade pieces, and play mini-games. It is built with React, Express, and MongoDB. I built the Showcase feature solo: users curate pieces into playlists and play them as a slideshow. Network Heartbeat Monitor is an uptime dashboard built by a team of four in three weeks with Node.js, Express, MongoDB, and Socket.IO. It pings registered URLs on a schedule and pushes live up/down status to a React dashboard. I built the synthetic-transaction system: scripted multi-step HTTP journeys, like login to checkout, that stop at the first broken step. Barta is a peer-to-peer barter marketplace built by a team of four with React, Express, Prisma, PostgreSQL, and Socket.IO. I was the main architect of the trust-and-safety system: AI content screening, reports and appeals, notifications, user blocking, and the moderation UI. The backend uses an outbox pattern and optimistic concurrency, so a crash cannot leave a post without its screening job Disquiet is my developer portfolio site, built solo with Astro, TypeScript, and Tailwind CSS and deployed on Vercel. I wrote seven architecture decision records before the first line of app code, then built a typed content layer and the work pages to match them.