Subscription Master

What I built

• Built a Spring Boot backend, live with 25 users, that detects subscriptions in Gmail via Google OAuth2 and the Gmail API, trusting only SPF/DKIM/DMARC-verified billing emails, powering a React + TypeScript frontend on Vercel.
• Replaced manual subscription entry and renewal tracking by deriving status from Gmail receipts, reminding users before each charge and flagging failed payments as Billing required, in-app, by Gmail and Web Push.
• Protected mailbox data by encrypting Google refresh tokens with AES-256-GCM, exchanging single-use 60-second login codes for JWTs, serving emails sanitized under a strict CSP, and hard-deleting all data on disconnect.
• Added an admin dashboard to audit Gmail detection for 25 users, with role checks that revoke access instantly.
• Set up a GitHub Actions and Jib pipeline to AWS EC2 that fails a release unless the new container passes a health check, behind Nginx TLS with PostgreSQL on Amazon RDS.
• Blocked 2 deploy misconfigurations in the Amazon RDS migration with JUnit tests on the Docker Compose and CI config, part of 471 tests (Testcontainers, WireMock) gating every pull request.

Stack