How should a webhook signature be verified?

Compute HMAC-SHA256 over the timestamp, a period, and the exact raw request body, then compare the expected and received signatures in constant time.

Can the same webhook event be received more than once?

Receivers should be idempotent and suppress duplicates using the x-farpy-event-id value.

How does FARPY retry failed webhook deliveries?

Failed deliveries use exponential retry for up to four delivery attempts. A successful 2xx response acknowledges delivery.

How long are failed webhook events retained?

Undelivered events remain in the durable webhook queue for failed-delivery retention. No public deletion interval is promised.

API

Signed render completion webhooks

Q: Which FARPY render webhook events are sent?

FARPY sends render.completed, render.failed, and render.cancelled terminal events.

Receive durable terminal delivery events for render.completed, render.failed and render.cancelled.

Delivery contract

Each event has a unique event ID and includes the x-farpy-event-id header.
Use the event ID for idempotency and duplicate suppression. Receivers must tolerate duplicate delivery.
Delivery is HTTPS-only. Private, loopback and other blocked addresses are rejected.
DNS is resolved and pinned for delivery to reduce rebinding risk.
Redirects are not followed. Configure the final HTTPS endpoint directly.
Return an HTTP 2xx response before the delivery timeout to acknowledge successful receipt.
Failed deliveries use exponential backoff for up to four delivery attempts.
Undelivered events remain in the durable webhook queue for failed-delivery retention. No public deletion interval is promised.
Successfully delivered event IDs are recorded to prevent duplicate redelivery.

Payload and signature verification

Each request includes these headers:

x-farpy-event-id
x-farpy-event-type
x-farpy-timestamp
x-farpy-signature

The JSON payload includes id, type, created_at and data.job_id.

{
  "id": "evt_example",
  "type": "render.completed",
  "created_at": 1785220000,
  "data": {
    "job_id": "job_example"
  }
}

Verify x-farpy-signature before trusting the payload. Compute HMAC-SHA256 with the webhook secret over the exact UTF-8 bytes of x-farpy-timestamp + "." + raw_request_body. The expected header value is v1=<hex_digest>. Use the raw request body; parsing and re-serializing JSON can change the signed bytes. Compare signatures with a constant-time comparison. Reject stale timestamps according to your receiver tolerance window to reduce replay risk, and suppress repeated event IDs.

Terminal events

render.completed
render.failed
render.cancelled

Treat delivery as a notification. Confirm canonical job status through the status endpoint before taking irreversible action.

Production flow

capabilities
pricing
upload
submit
status
download
receipt
proof

API properties

API-key authentication
100 MiB upload limit
Idempotent submission support
60 requests per minute plus burst capacity
Cancellation before worker claim
Signed terminal webhooks
Receipts and proof artifacts
Machine-readable OpenAPI 3.1 specification

Start here

curl -sS https://farpy.com/v1/capabilities \
  -H "Authorization: Bearer $FARPY_API_KEY"