Backend Developer for TForce Freight API Integration (OAuth2 + REST)

I need a developer to integrate the TForce Freight "Get Rate" API into an existing web-based freight calculator. The situation: I run a door manufacturing company. I've already built a freight calculator (in Lovable, a web app) that takes a customer's order and outputs the pallet dimensions, weights, and shipping details. That part is done and working. What I need is for those outputs to be sent to the TForce Freight rating API so the tool returns a live freight quote automatically, instead of my employee typing everything into TForce's portal by hand. The specific work: Connect to the TForce Freight Get Rate API (endpoint: POST (link removed)) Implement OAuth 2.0 client-credentials authentication (token fetch + refresh) plus the API subscription key Securely store my API credentials so they are never exposed in the frontend/browser — must be handled server-side or via secure environment variables Map my calculator's existing output (origin zip, destination zip, pallet weight, dimensions, accessorials) to the API's request format Return the freight rate into my app and handle errors gracefully (API down, invalid request, etc.) What's already done: The full calculator and all pallet/weight logic is built and working I have TForce developer portal access and will provide credentials securely (not in this job post) TForce provides API documentation, sample request, and sample response What I'm looking for: Experience with REST API integration and OAuth 2.0 client-credentials flow Backend experience (Node.js or similar) — the secret cannot live in the browser Someone who communicates clearly and asks questions upfront This is a small, well-defined job — a single endpoint with standard auth. I have a detailed spec I'll share with the developer I hire. In your proposal, please tell me: what OAuth grant type does this integration use? (This confirms you read the post.)