Create Dynamic Workflows Programmatically via Webhooks & n8n API

Overview

This workflow exposes an HTTP endpoint (webhook) that accepts a JSON definition of an n8n workflow, validates it, and—if everything is correct—dynamically creates that workflow in the n8n instance via its internal API. If any validation fails or the API call encounters an error, an explanatory message with details is returned.

Workflow Diagram

Webhook
   │
   ▼
Validate JSON ── fails validation ──► Validation Error
   │
   └─ passes ─► Validation Successful?
                           │
                           ├─ true ─► Create Workflow ──► API Successful? ──► Success Response
                           │                                 │
                           │                                 └─ false ─► API Error
                           └─ false ─► Validation Error

Step-by-Step Details

1. Webhook

• Type: Webhook (POST)
• Path: /webhook/create-workflow
• Purpose: Expose a URL to receive a JSON definition of a workflow.
• Expected Input: JSON containing the main workflow fields (name, nodes, connections, settings).

2. Validate JSON

• Type: Code Node (JavaScript)

• Validations Performed:

  • Ensure that payload exists and contains both name and nodes.
  • Verify that nodes is an array with at least one item.
  • Check that each node includes the required fields: id, name, type, position.
  • If missing, initialize connections, settings, parameters, and typeVersion.

• Output if Error:

  { "success": false, "message": "<error description>" }
  

• Output if Valid:

  {
    "success": true,
    "apiWorkflow": {
      "name": payload.name,
      "nodes": payload.nodes,
      "connections": payload.connections,
      "settings": payload.settings
    }
  }
  

3. Validation Successful?

• Type: IF Node

• Condition: $json.success === true

• Branches:

  • true: proceed to Create Workflow
  • false: route to Validation Error

4. Create Workflow

• Type: HTTP Request (POST)
• URL: http://127.0.0.1:5678/api/v1/workflows
• Authentication: Header Auth with internal credentials
• Body: The apiWorkflow object generated earlier
• Options: continueOnFail: true (to handle failures in the next IF)

5. API Successful?

• Type: IF Node

• Condition: $response.statusCode <= 299

• Branches:

  • true: proceed to Success Response
  • false: route to API Error

6. Success Response

• Type: SET Node

• Output:

  {
    "success": "true",
    "message": "Workflow created successfully",
    "workflowId": "{{ $json.data[0].id }}",
    "workflowName": "{{ $json.data[0].name }}",
    "createdAt": "{{ $json.data[0].createdAt }}",
    "url": "http://localhost:5678/workflow/{{ $json.data[0].id }}"
  }
  

7. API Error

• Type: SET Node

• Output:

  {
    "success": "false",
    "message": "Error creating workflow",
    "error": "{{ JSON.stringify($json) }}",
    "statusCode": "{{ $response.statusCode }}"
  }
  

8. Validation Error

• Type: SET Node

• Output:

  { "success": false, "message": "{{ $json.message }}" }
  

Example Webhook Request

curl --location --request POST 'http://localhost:5678/webhook/create-workflow' \
--header 'Content-Type: application/json' \
--data-raw '{
  "name": "My Dynamic Workflow",
  "nodes": [
    {
      "id": "start-node",
      "name": "Start",
      "type": "n8n-nodes-base.manualTrigger",
      "typeVersion": 1,
      "position": [100, 100],
      "parameters": {}
    },
    {
      "id": "set-node",
      "name": "Set",
      "type": "n8n-nodes-base.set",
      "typeVersion": 1,
      "position": [300, 100],
      "parameters": {
        "values": {
          "string": [
            { "name": "message", "value": "Hello from a webhook-created workflow!" }
          ]
        }
      }
    }
  ],
  "connections": {
    "Start": {
      "main": [
        [ { "node": "Set", "type": "main", "index": 0 } ]
      ]
    }
  },
  "settings": {}
}'

Expected Success Response

{
  "success": "true",
  "message": "Workflow created successfully",
  "workflowId": "abcdef1234567890",
  "workflowName": "My Dynamic Workflow",
  "createdAt": "2025-05-31T12:34:56.789Z",
  "url": "http://localhost:5678/workflow/abcdef1234567890"
}

Validation Error Response

{
  "success": false,
  "message": "The 'name' field is required in the workflow"
}

API Error Response

{
  "success": "false",
  "message": "Error creating workflow",
  "error": "{ ...full API response details... }",
  "statusCode": 401
}