Transparent Tracking Pixel for Email Open Detection

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        "content": "## 📬 Workflow: Transparent Tracking Pixel for Email Open Detection\n\n### 📌 Description\nThis workflow serves a **1x1 transparent PNG image** via a webhook, which can be embedded in an email to **track when the email is opened**. When the image is loaded by the recipient's email client, the webhook is triggered, optionally capturing a `userId` to identify who opened the email.\n\n---\n\n### 📂 Workflow Steps\n\n1. **Webhook Trigger** (`Request img`)\n   - **Path:** `/webhook/change-with-your-id`\n   - Triggered by an HTTP request (e.g. when the image is loaded in an email).\n   - Accepts a query parameter `id` to identify the recipient.\n\n2. **Set Base64 Data** (`Create data pix`)\n   - Creates a variable `data` containing a Base64-encoded transparent PNG image (1x1 pixel).\n\n3. **Convert to Binary** (`Create img bin`)\n   - Converts the Base64 `data` string into a binary file.\n   - Sets MIME type to `image/png`.\n\n4. **Respond to Webhook** (`Respond to Webhook`)\n   - Sends the binary image file in the HTTP response.\n\n5. **Logging** (`Do anything to log`)\n   - Placeholder node to log or process the `id` or request metadata.\n   - You can access the `id` using `{{$json[\"query\"][\"id\"]}}`.\n   - You can also use any parameter you want\n\n---\n\n### ✉️ How to Use in Emails\n\nEmbed the image in an HTML email like this:\n\n```html\n<img src=\"https://<your-n8n-instance>/webhook/db4880e7-2134-4994-94e5-a4a3aa120440?id=1234\" width=\"1\" height=\"1\" style=\"display:none;\" alt=\"\" />\n```\n\nWhen the email is opened and the image is loaded, the workflow will be triggered.\n\n---\n\n### 🛠️ Notes\n- Some email clients block images by default; this may prevent tracking.\n- You can enhance the workflow to store open events in a database, log the timestamp, IP, or user agent.\n- Make sure to comply with data privacy and consent regulations (e.g. GDPR)."
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