Webhooks Overview

Webhooks let your application react when resources change in Probo without polling the API. A subscription connects one HTTPS endpoint to a set of events in one organization. When an event occurs, Probo sends a signed POST request containing a JSON snapshot of the affected resource.

Common uses include synchronizing users and third parties, starting document approval workflows, and recording compliance events in another system.

How it works

1. Expose an HTTPS endpoint

   Your endpoint must accept POST requests with an application/json body.

2. Create a subscription

   In Probo, open Settings > Webhooks, enter the endpoint URL, and select the events to receive. You can also manage subscriptions with the CLI.

3. Verify every delivery

   Verify the signature against the raw request body and reject stale timestamps before parsing or acting on the payload.

4. Acknowledge quickly

   Persist or enqueue the event, then return an accepted 2xx response. Perform slow work asynchronously.

Endpoint requirements

• The URL must use HTTPS.
• The endpoint must return 200, 201, 202, or 204.
• The complete response must arrive within 30 seconds.

Any other status, connection error, or timeout marks the delivery as failed. Probo does not retry failed deliveries, so monitor delivery history and design a recovery process for missed events.

Root envelope

Every delivery body is a JSON object with a fixed root envelope. Resource-specific fields live under data (and optionally updatedFrom) — they are never promoted to the root.

{
  "eventId": "whevt_01ABC123",
  "subscriptionId": "whsub_01DEF456",
  "organizationId": "org_01GHI789",
  "eventType": "document:updated",
  "createdAt": "2026-07-15T10:30:00Z",
  "data": {
    "id": "doc_01VWX234",
    "title": "Information Security Policy"
  },
  "updatedFrom": {
    "id": "doc_01VWX234",
    "title": "InfoSec Policy"
  }
}

Root field	Type	Always present	Description
eventId	string	Yes	Unique delivery ID. Use it as an idempotency key
subscriptionId	string	Yes	Webhook subscription that received the event
organizationId	string	Yes	Organization where the event occurred
eventType	string	Yes	Wire-format event name (e.g. document:updated, third-party:created)
createdAt	string	Yes	When the event was created (RFC 3339)
data	object	Yes	Current resource payload for the event. Shape depends on eventType — see Event Types
updatedFrom	object	No	Present only on *:updated events. Full snapshot of the same resource shape as data, taken before the update. Omitted for create, delete, archive, signature, and other non-update events

Process a delivery safely

1. Verify the signature using the headers and untouched request body.
2. Parse the JSON only after verification succeeds.
3. Confirm organizationId and eventType are ones your endpoint expects.
4. Atomically record eventId before producing side effects. Ignore an ID you have already processed.
5. Enqueue the event and return a successful response.

For update events, compare updatedFrom with data to identify the change. Resource IDs such as a document or user ID are nested under data; they are not root fields.

HTTP headers

Each request also carries metadata in headers. Some headers mirror root envelope fields so you can route or reject a delivery before parsing the body.

Header	Mirrors body field	Description
Content-Type	—	Always application/json
X-Probo-Webhook-Event	eventType	Wire-format event name (e.g. document:updated)
X-Probo-Webhook-Organization-Id	organizationId	Organization ID
X-Probo-Webhook-Timestamp	—	Unix timestamp in seconds used when computing the signature
X-Probo-Webhook-Signature	—	Hex-encoded HMAC-SHA256 of {timestamp}:{rawBody}
X-Probo-Webhook-Host	—	Hostname of the Probo instance that sent the delivery (for multi-region / self-hosted receivers)

Header vs body

Use case	Prefer
Signature verification	Headers (X-Probo-Webhook-Timestamp, X-Probo-Webhook-Signature) + raw body bytes
Fast allow/deny before JSON parse	Headers (X-Probo-Webhook-Event, X-Probo-Webhook-Organization-Id, X-Probo-Webhook-Host)
Business logic / diffs	Root envelope + data / updatedFrom
Idempotency	Root eventId

subscriptionId and createdAt exist only in the body root — they are not duplicated as headers.

Signing secret

Probo generates a signing secret prefixed with whsec_ for each subscription. Store it in a secret manager, scope it to the receiving service, and never log it or include it in client-side code. The secret is required to verify webhook signatures.

Delivery behavior

• Probo polls for pending events approximately every 5 seconds and processes them sequentially.
• A delivery succeeds only when the endpoint returns 200, 201, 202, or 204 within 30 seconds.
• Failed deliveries are not retried automatically.
• Probo stores the response status, headers, and up to 64 KB of the response body for troubleshooting.
• Delivery status is PENDING, SUCCEEDED, or FAILED.

Review delivery history under Settings > Webhooks. Avoid returning secrets or sensitive records in your response body because the response is retained for debugging.

Do not depend on the webhook as your only copy of data

Because failed deliveries are not retried, use webhooks as change notifications. If missing an event would be critical, periodically reconcile your local state with the Probo API.

Receiver checklist

• Preserve the raw body until signature verification is complete.
• Accept requests only from expected organizations and event types.
• Use eventId to make processing idempotent.
• Queue work before sending the response.
• Alert on FAILED deliveries and reconcile missed changes.
• Ignore unknown JSON fields so additive payload changes do not break your receiver.

Next steps

Event Types See all available webhook events and their payloads

Signature Verification Verify that webhook requests come from Probo

n8n Trigger Start n8n workflows from Probo webhook events