Formstack Webhooks

Formstack Forms (formstack.com) sends submission data to your endpoint through a WebHook submit action — labelled "Send Data to an External URL (WebHook)" in the form builder. One HTTP POST per form submission.

Scope. This skill is about Formstack Forms only. It does not cover Formstack Documents (formerly WebMerge, which has its own separate "Webhook Delivery" feature), Formstack Sign (formerly InsureSign), or the Salesforce-packaged products. Those are different surfaces with different payloads. A Documents delivery is easy to tell apart: it posts merge_id, handshake, file_name and a base64 file_contents, with a WebMerge user-agent and no signature header. A Forms delivery posts FormID and UniqueID with a FormstackWebhook/1.0 user-agent.