NorthGateOS API Documentation

Overview

The NorthGateOS REST API operates over HTTPS and returns JSON-encoded responses. Standard HTTP response codes are used to indicate request status.

Authentication

Authenticate your requests by including your secret API key in the Authorization header:

Authorization: Bearer ng_live_sec_************************

Submit an Invoice

Submit an invoice payload for pre-flight validation and transmission to the Nigeria Revenue Service (NRS):

curl -X POST https://api.northgateds.com.ng/v1/invoices \
  -H "Authorization: Bearer $NG_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "invoice_number": "INV-2026-0418",
    "issue_date": "2026-10-14",
    "buyer": {
      "tin": "5432109876",
      "name": "Sample Retail Ltd",
      "address": "Victoria Island, Lagos"
    },
    "items": [
      {
        "description": "Enterprise Software License",
        "quantity": 1,
        "unit_price": 2000000,
        "tax_rate": 0.075
      }
    ]
  }'

Webhooks

NorthGateOS provides webhooks to notify your backend asynchronously when an invoice has been cleared or rejected by NRS:

• invoice.approved — Dispatched when NRS MBS validates the invoice and issues an IRN.
• invoice.rejected — Dispatched if validation fails (e.g. invalid buyer TIN).