Convert Mobile APIs to Node

I'm rebuilding the entire server side of my Android and iOS apps in Node.js. The current apps talk exclusively to a set of RESTful endpoints, and those endpoints handle three critical jobs for me right now: authenticating users, processing payments (using the CCAvenue gateway), and keeping local data in sync with the cloud.
We also use WooCommerce custom REST API and its database for other core functions (products, orders, etc.) — but payments go through CCAvenue, not WooCommerce.

I want every one of those workflows reproduced in Node so I can move faster with new features and scale without the legacy overhead.

You'll have full freedom to modify the back-end codebase, database schemas, and deployment scripts as needed. All existing REST routes must remain available (or be cleanly proxied) so the mobile clients continue to work while we test the new stack. Once the Node service passes integration tests and the apps run error-free against it, we'll decommission the old API.

I'll provide the current API documentation, sample requests, test accounts, and direct access to the staging servers the apps already point to. Your deliverable is a production-ready Node.js backend — well-structured, documented, and unit-tested — that mirrors the functionality of the existing service and is ready for me to drop into our CI/CD pipeline.