QuickBooks Invoice Automation

I need a small service that connects our third-party platform to QuickBooks Online through the official API. Its single purpose is to analyse each incoming invoice, detect rounding errors or other amount mismatches, and resolve them automatically.

Here is the flow I have in mind:

• When the external system pushes an invoice, the service checks every line and total.
• If the variance is within a configurable tolerance, it quietly posts the adjusting entry or creates the needed credit memo and applies it to the invoice.
• If the variance is larger, the service still posts the adjustment but also flags the invoice for review and sends a notification to the accounting channel.

The adjustment logic, flagging method (custom field, class, or other), and notification channel are all open to your recommendation as long as they stay within QuickBooks API guidelines.

Deliverables
• Clean, well-documented source code (Node, Python, or .NET preferred)
• Deployment instructions for an Azure Function, AWS Lambda, or a lightweight VPS
• QuickBooks sandbox setup with test data showing successful rounding-error corrections and mismatch flags
• Postman collection (or Swagger file) for any endpoints the service exposes

Acceptance criteria
1. An invoice containing a rounding variance ≤ tolerance is adjusted and closed without human intervention.
2. An invoice containing a larger variance is adjusted, marked “Needs-Review,” and triggers an email/Slack alert.
3. Every action is logged with enough detail to audit the change in QuickBooks.

Please only take this on if you have shipped similar QuickBooks API automations before; a short note or link to a past project will help me choose quickly.