MERN Payment Reminder Web App

I need a full MERN-stack website that lets me create subscription plans, store customer records and automatically nudge them when a payment date is approaching or overdue. The tech is non-negotiable—MongoDB, Express.js, React.js and Node.js—so you should already be comfortable wiring these pieces together.

Core workflow
• I log in through a third-party OAuth provider (Google, GitHub or similar).
• Inside an admin dashboard I can add or import customers, set an amount, a due date and a reminder schedule.
• The system then fires automated reminders through both email and SMS without me lifting a finger.

Key requirements
• Automated reminders via email and SMS (use Nodemailer + Twilio—or any battle-tested alternative you prefer).
• Configurable reminder cadence (e.g., 7 days before, on due date, X days after).
• Simple customer & subscription table stored in MongoDB with CRUD operations exposed through a secure REST API.
• React.js front-end with a clean, mobile-responsive UI.
• Production-ready Node/Express server with environment-based configuration and error handling.
• Deployment scripts or instructions so I can push the app live on a VPS or cloud service.

Acceptance criteria
1. I can sign in with Google and land on the dashboard.
2. Creating a customer + due date instantly schedules the correct reminders.
3. Both an email and an SMS reach my test number/address at the set times.
4. Code is organized, lint-clean and delivered through a Git repo plus a short README for setup.

If this sounds straightforward to you, let’s get started—I’m ready to review your approach and timeline.