Invoice Approval with Verifiable Decision Receipts

The workflow JSON

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{
  "name": "Invoice Approval with Verifiable Decision Receipts",
  "nodes": [
    {
      "parameters": {
        "httpMethod": "POST",
        "path": "invoice-approval",
        "options": {},
        "responseMode": "responseNode"
      },
      "id": "14831c8e-ba43-4d8d-ac1c-5b44042eac43",
      "name": "New Invoice",
      "type": "n8n-nodes-base.webhook",
      "typeVersion": 2.1,
      "position": [
        0,
        300
      ]
    },
    {
      "parameters": {
        "modelId": {
          "__rl": true,
          "mode": "list",
          "value": "gpt-4o",
          "cachedResultName": "GPT-4O"
        },
        "messages": {
          "values": [
            {
              "role": "system",
              "content": "=You are an accounts-payable AI agent. Analyze the invoice and decide APPROVE or HOLD. Return JSON: {\"decision\":\"APPROVE|HOLD\",\"reason\":\"...\",\"amount\":0,\"vendor\":\"...\"}."
            },
            {
              "content": "=Analyze this invoice and return JSON only.\n\nInvoice:\n{{ JSON.stringify($json.body) }}"
            }
          ]
        },
        "jsonOutput": true,
        "options": {}
      },
      "id": "539ff727-7804-476f-8603-90cf9332c1a1",
      "name": "AI Invoice Analysis",
      "type": "@n8n/n8n-nodes-langchain.openAi",
      "typeVersion": 2.1,
      "position": [
        220,
        300
      ],
      "credentials": {
        "openAiApi": {
          "name": "<your credential>"
        }
      }
    },
    {
      "parameters": {
        "conditions": {
          "options": {
            "caseSensitive": true,
            "leftValue": "",
            "typeValidation": "loose"
          },
          "conditions": [
            {
              "id": "5fe897bd-603f-4fe0-bd58-4cedfba9d4e0",
              "leftValue": "={{ $json.message.content.decision }}",
              "rightValue": "APPROVE",
              "operator": {
                "type": "string",
                "operation": "equals"
              }
            }
          ],
          "combinator": "and"
        },
        "options": {}
      },
      "id": "f1aea1f2-36c9-4a4c-9d34-7f75ded77c5e",
      "name": "IF Approved",
      "type": "n8n-nodes-base.if",
      "typeVersion": 2.2,
      "position": [
        440,
        300
      ]
    },
    {
      "parameters": {
        "operation": "generateReceipt",
        "agentName": "InvoiceApprovalAgent",
        "workflowName": "={{ $workflow.name }}",
        "action": "={{ 'Invoice ' + $json.message.content.decision }}",
        "decision": "={{ JSON.stringify($json.message.content) }}",
        "additionalFields": {
          "modelProvider": "openai",
          "modelUsed": "gpt-4o",
          "decisionType": "invoice_approval",
          "riskLevel": "medium",
          "humanReview": false,
          "policies": "ap-controls-v2, sox-segregation",
          "permissions": "invoice.approve, payment.schedule",
          "tags": "finance, invoice, ap"
        }
      },
      "id": "2d20ec38-98f0-49b7-931a-73c110b17bde",
      "name": "Signatrust: Receipt",
      "type": "n8n-nodes-signatrust.signatrust",
      "typeVersion": 1,
      "position": [
        660,
        200
      ],
      "credentials": {
        "signatrustApi": {
          "name": "<your credential>"
        }
      }
    },
    {
      "parameters": {
        "method": "POST",
        "url": "https://httpbin.org/post",
        "options": {},
        "sendBody": true,
        "bodyParameters": {
          "parameters": [
            {
              "name": "invoice",
              "value": "={{ $('New Invoice').item.json.body }}"
            },
            {
              "name": "receipt_id",
              "value": "={{ $json.id }}"
            }
          ]
        }
      },
      "id": "3b3ed7f4-52ad-49d9-91c9-dc4b1e1f082d",
      "name": "Post to ERP",
      "type": "n8n-nodes-base.httpRequest",
      "typeVersion": 4.2,
      "position": [
        880,
        200
      ]
    },
    {
      "parameters": {
        "respondWith": "json",
        "responseBody": "={{ { \"status\": \"HOLD\", \"detail\": $('AI Invoice Analysis').item.json.message.content } }}",
        "options": {}
      },
      "id": "7e90dc36-a939-41ac-92b0-ca2986323fe8",
      "name": "Respond Hold",
      "type": "n8n-nodes-base.respondToWebhook",
      "typeVersion": 1.1,
      "position": [
        660,
        440
      ]
    },
    {
      "parameters": {
        "content": "## Invoice Approval + Signatrust\nAI reviews each invoice and approves or holds it. The approval is signed into a Decision Receipt that proves **why** it was approved, **when**, and **by which agent** \u2014 ready for SOX/audit.",
        "height": 200,
        "width": 420,
        "color": 5
      },
      "id": "a06fa2a4-754f-4f72-806c-7eba5d283b28",
      "name": "Sticky Note 782fd8",
      "type": "n8n-nodes-base.stickyNote",
      "typeVersion": 1,
      "position": [
        -40,
        30
      ]
    }
  ],
  "connections": {
    "New Invoice": {
      "main": [
        [
          {
            "node": "AI Invoice Analysis",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "AI Invoice Analysis": {
      "main": [
        [
          {
            "node": "IF Approved",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "IF Approved": {
      "main": [
        [
          {
            "node": "Signatrust: Receipt",
            "type": "main",
            "index": 0
          }
        ],
        [
          {
            "node": "Respond Hold",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Signatrust: Receipt": {
      "main": [
        [
          {
            "node": "Post to ERP",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "active": false,
  "settings": {
    "executionOrder": "v1"
  },
  "tags": [
    {
      "name": "Invoice Approval \u2014 Finance"
    },
    {
      "name": "Invoice Approval \u2014 Invoice"
    },
    {
      "name": "Signatrust (2)"
    },
    {
      "name": "Invoice Approval \u2014 AI"
    }
  ],
  "meta": {
    "templateCredsSetupCompleted": false
  },
  "versionId": "cb75b480-186d-4973-a86e-df2d9eeb656f"
}

Credentials you'll need

Each integration node will prompt for credentials when you import. We strip credential IDs before publishing — you'll add your own.

• openAiApi
• signatrustApi

About this workflow

Invoice Approval with Verifiable Decision Receipts. Uses openAi, n8n-nodes-signatrust, httpRequest. Webhook trigger; 7 nodes.

Source: https://github.com/abokenan444/n8n-signatrust-workflows/blob/main/workflows/02-invoice-approval.json — original creator credit. Request a take-down →

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