WordPress.com Webhooks

WordPress.com (Automattic's hosted WordPress service) has a native webhooks feature under Settings → Webhooks, documented at wordpress.com/support/webhooks/. An admin picks an action (the hook), ticks the fields to include, and enters a URL. When the action fires, WordPress.com POSTs the selected fields to that URL.

Three things make this unlike most providers in this repo:

1. The deliveries are UNSIGNED. No HMAC, no signature header, no secret, no timestamp, no token, no custom headers, no handshake. The docs describe only three inputs — action, fields, URL — and nothing to verify.
2. The body is a flat form-encoded key/value set, not a JSON envelope. No type, no data object, no event id. The discriminator is the hook field, whose value is the action name.
3. Only the fields the admin ticked are sent. Every field is optional except hook — never assume a field is present, and every value arrives as a string.