If you’re not looking to build on top of the API, you can use the no-code webapp at https://app.useinkless.com/

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Overview

Webhooks allow your application to receive real-time notifications when important events occur in your e-sign workflow, such as when a document is signed or a finalized PDF is generated. By registering a webhook, you can automate downstream actions (e.g., send emails, update your CRM, etc.) whenever these events happen.

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Registering a Webhook

To receive webhook notifications, you must first register your webhook endpoint using the /registerWebhook API.

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Endpoint

POST /registerWebhook

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Request Headers

  • x-api-key: (required) Your API key for authentication.

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Request Body

{
  "user_id": "your-user-id",
  "url": "https://yourdomain.com/webhook-endpoint",
  "eventType": "document.signed", // or "document.finalized"
  "secret": "optional-secret-key"
}
  • user_id: Your user ID (provided when you sign up for API access).
  • url: The HTTPS endpoint that will receive webhook events.
  • eventType: The event to subscribe to. Supported values:
    • document.signed — triggered when a recipient signs a document.
    • document.finalized — triggered when the final, signed PDF is available.
  • secret (optional): If provided, webhook payloads will be signed so you can verify authenticity.
Example Request 
curl -X POST https://api.useinkless.com/registerWebhook \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "user_id": "user-123",
    "url": "https://yourdomain.com/webhook",
    "eventType": "document.signed"
  }'
Response 
{
  "message": "Webhook registered",
  "webhook": {
    "webhook_id": "abc123",
    "url": "https://yourdomain.com/webhook",
    "eventType": "document.signed"
  }
}

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Supported Webhook Events

Event NameDescription
document.signedTriggered when a recipient signs a document.
document.finalizedTriggered when the final signed PDF is available to owner.

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Webhook Payloads

When your webhook is triggered, your endpoint will receive a POST request with a JSON payload. The structure depends on the event.

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document.signed Event

{
  "event": "document.signed",
  "pdf_id": "pdf-123",
  "recipient": {
    "name": "Recipient Name",
    "email": "recipient@example.com",
    "recipientHash": "hash123"
  },
  "completed_fields": [
    // ... array of completed field objects
  ],
  "status": "signed"
}
  • event: The event type.
  • pdf_id: The unique identifier for the document.
  • recipient: The recipient who signed (name, email, and a unique hash).
  • completed_fields: Information about completed fields (see API reference for structure).
  • status: The current status of the document.

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document.finalized Event

{
  "event": "document.finalized",
  "pdf_id": "pdf-123",
  "final_pdf_url": "https://s3.amazonaws.com/your-bucket/final_document.pdf"
}
  • event: The event type.
  • pdf_id: The unique identifier for the document.
  • final_pdf_url: A secure, time-limited URL to download the finalized PDF.

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Authenticating Webhook Requests

If you provided a secret when registering your webhook, each webhook request will include a signature header (x-webhook-signature) that you can use to verify the authenticity of the payload. (See below for verification instructions.)

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Handling Webhooks

Your endpoint should: Respond with HTTP 200 OK as soon as possible. Validate the payload signature if a secret is used. Process the event according to your business logic. Example Webhook Handler (Node.js/Express) 
app.post('/webhook', express.json(), (req, res) => {
  const event = req.body.event;
  if (event === 'document.signed') {
    // Handle document signed
  } else if (event === 'document.finalized') {
    // Handle finalized PDF
  }
  res.status(200).send('OK');
});

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Authentication

All API endpoints are authenticated using Bearer tokens or API keys. Email hello@useinkless.com to get started with your API key. If you need more details or want to see sample payloads for other events, please reach out to support.