Electronic Signature Webhooks: Events and Callbacks

What are electronic signature webhooks?

Electronic signature webhooks are event-triggered notifications a signing service sends to a configured application endpoint. They let an application react to supported changes, such as a request completing or being declined, without repeatedly asking for updates at fixed intervals.

The service sends a callback, commonly an HTTP POST containing structured event data. The receiving application decides what to do with that information. Receiving the callback and successfully completing a downstream business action are different outcomes.

How do they differ from API polling?

With polling, an application repeatedly queries the signing API for current information. With a webhook, the service initiates a notification for a subscribed event. Some integrations still use an API query to reconcile status or retrieve the actual signed record.

Sign.Plus’s official webhook guide documents envelope events for completion, expiration, decline, voiding and audit-trail activity. These are different signals: an audit-trail notification is not interchangeable with a completion event, and a callback does not itself contain or replace every relevant signed artifact.

What needs to be checked before acting?

• Origin and authenticity: follow the provider’s documented verification method and use HTTPS. A JSON payload claiming “completed” is not trustworthy solely because it reached the endpoint.
• Event meaning: distinguish the relevant request and event from a different recipient, file or business transaction.
• Repeated processing: design the business action so a repeated notification does not create duplicate records or repeated fulfillment.
• Failures and recovery: check documented delivery, retry and reconciliation behavior instead of assuming instant, ordered or exactly-once delivery.

GitHub’s official webhook guidance illustrates why source verification, event checks and controlled processing matter; its headers and timing rules are specific to GitHub.

What does a completion callback prove?

It reports the service’s event within the defined workflow. It does not independently establish every signer’s legal authority or the enforceability of the agreement. Preserve the relevant signed documents and evidence, and check the current request when a notification is missing or ambiguous.

For signing inside an application, a browser completion screen should not be confused with a server notification. An AI assistant tracking progress likewise needs the actual service result rather than inferring success from its own earlier send action.