Delivery
Content type
Fractal ID uses application/json content type to deliver the JSON payload directly as the body of the POST request.
Expected response
Fractal ID expects your server to reply with response code 2xx to identify successful delivery. All response codes outside this range, including 3xx codes, will indicate to Fractal ID that you did not receive the webhook.
Fractal ID will make sure to send notification successfully at least once to the client. There is a possibility of receiving the same successful webhook notification multiple times, but in very rare cases. This means you should likely want to ensure your endpoint is idempotent.
Retrying sending notifications
Fractal ID will retry to send webhooks notification if:
Client server failed to respond in 10 seconds.
Client server is unavailable (network errors).
Client server returns other response code than
2xx.
Fractal ID uses exponential backoff to retry events.
Example retry times table
Retries
Next retry in seconds
1
20
2
40
3
80
5
320
10
10240
15
86400
20
86400
Order of delivery
The order of callbacks to webhook endpoints is not guaranteed.
For, e.g., two subsequent status changes, if initial attempt to deliver first notification fails it's being scheduled for retry. Second notification may arrive earlier than the retry on the first notification happens.
To mitigate the risk of setting incorrect user status based on received webhook callbacks we encourage you to keep track of the timestamp fields of the status change notifications and compare them internally, or retrieve user information upon getting a webhook callback.
Example delivery
Suppose for the given example the secret token is 9d7e80c0f169ab94d34392d64617b7517fb07c40.
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