E-signature webhooks for signing events

Add an endpoint

In SignWith, open Settings → Webhooks, add your URL and choose the events you want. SignWith then sends a POST with a JSON body to that URL for each event.

Webhook URLs must be public http:// or https:// addresses. URLs that point at private, loopback or link-local networks (such as localhost, 10.0.0.0/8 or 192.168.0.0/16) are rejected when you save the endpoint and again at delivery time. To test on your own machine, expose it with a tunnel such as ngrok.

Events

Each event's payload and an example are on the webhook events page.

The payload

{
  "id": "evt_7Qm2Vt9sKd3LpXa8RzYw1bNc",
  "type": "signer.signed",
  "created_at": "2026-09-27T10:15:00Z",
  "data": { "object": "signer", "id": 9121, ... }
}

• id is unique per event and stays the same across retries. Store it and ignore events you've already handled.
• type is the event name, also sent in the X-SignWith-Event header.
• data uses the same shapes as API responses and shows the object as it is at delivery time. If you need the latest state, fetch it with the API.

Headers

Any custom headers you set on the endpoint are sent too.

Verify every request before you trust it: anyone can send a POST to a public URL. Verifying webhook signatures has the code for Node and Python.

Respond quickly, and expect retries

Return any 2xx status within 30 seconds. Do slow work, such as downloading the signed PDF, after you respond, for example in a background job.

Other responses, timeouts and connection errors are retried with exponential back-off: after 1, 2, 4, 8 minutes and so on. Each event is delivered at most 10 times in total, the first attempt plus up to 9 retries. Because an event can arrive more than once, use its id to handle it only once.

A typical handler

When a document is completed, download the signed files:

1. Subscribe to signature_request.completed.
2. Verify the signature, check you haven't seen the event id before, and respond 200.
3. Read data.documents and data.audit_trail_url from the payload. If a link is null, fetch the signature request again shortly afterwards with GET /signature_requests/{id}.

Send a test event

The Send test event button on a webhook's settings page sends a webhook.test event straight away, whatever events the endpoint is subscribed to. It's not retried. Use it to check that your endpoint is reachable and that signature verification works.