Backend API for JS Browser Extension

The front-end of my JavaScript browser extension is complete and running smoothly; what is missing is the server side. I now need a backend that focuses on clean, reliable API integration—specifically connecting the extension to third-party services.

Here is the flow I am aiming for: when a user performs an action inside the extension, it should call my backend, which then talks to the chosen external API (Google, Facebook, Twitter, or any similar platform we agree on), processes the response, and returns streamlined data back to the client in JSON.

Key points I care about:
• A lightweight Node.js (or equivalent) service with clear folder structure.
• Secure handling of API keys, tokens, and refresh flows.
• Well-documented endpoints so I can keep iterating on the front-end without guessing payload formats.
• Error handling and simple logging so I can trace issues quickly.

Deliverables will be the complete backend source, a short README with setup instructions, and a quick screen share or video that walks through the endpoints in action. Once this scaffold is in place, I can extend the extension’s features confidently, knowing every server call is ready for production.