Webhooks | XID

Subscribe to XID events and receive signed HTTP payloads when users, sessions, and organizations change.

Event naming

Events follow the pattern <object>.<action>. Each event carries a stable type name, a unique svix-id, and an ISO 8601 timestamp.

Object	Actions
`user`	created, updated, deleted
`session`	created, ended, removed, revoked
`organization`	created, updated, deleted
`organizationMembership`	created, updated, deleted
`organizationInvitation`	created, accepted, revoked
`organizationDomain`	created, updated, deleted, verified, verification_failed
`authentication`	password_succeeded, password_failed, passkey_succeeded, passkey_failed, mfa_succeeded, mfa_failed, oauth_succeeded, oauth_failed, sso_succeeded, sso_failed, magic_auth_succeeded, magic_auth_failed, email_verification_succeeded, email_verification_failed, radar_risk_detected
`connection`	activated, deactivated, deleted, saml_certificate_renewed, renewal_required
`dsync`	activated, deleted, user.created, user.updated, user.deleted, group.created, group.updated, group.deleted, group.user_added, group.user_removed
`role`	created, updated, deleted
`permission`	created, updated, deleted
`email`	created (fired when the developer takes over sending)
`sms`	created (fired when the developer takes over sending)
`billing`	subscription.created, subscription.updated, paymentAttempt.succeeded, paymentAttempt.failed

Payload structure

Every webhook delivery is an HTTP POST with Content-Type: application/json. The body contains type, data, and top-level metadata headers.

{
  "type": "user.created",
  "data": {
    "id": "usr_01abc",
    "email_addresses": [{ "email_address": "alice@example.com" }],
    "created_at": 1700000000000
  }
}

Signature verification

XID signs every delivery with HMAC-SHA256. Verify the signature before processing the payload. Reject deliveries older than 5 minutes to prevent replay attacks.

Header	Description
`svix-id`	Unique message ID. Use this to deduplicate retried deliveries.
`svix-timestamp`	Unix seconds when the message was sent.
`svix-signature`	Base64-encoded HMAC-SHA256 of `${svix-id}.${svix-timestamp}.${raw-body}` using the endpoint signing secret.

// Node.js / Cloudflare Workers example
async function verifyWebhook(request, secret) {
  const svixId = request.headers.get('svix-id')
  const svixTimestamp = request.headers.get('svix-timestamp')
  const svixSignature = request.headers.get('svix-signature')
  const body = await request.text()

  // Reject messages older than 5 minutes
  const ts = Number(svixTimestamp)
  if (Math.abs(Date.now() / 1000 - ts) > 300) {
    throw new Error('webhook timestamp out of tolerance')
  }

  const signedContent = `${svixId}.${svixTimestamp}.${body}`
  const keyData = Uint8Array.from(atob(secret), c => c.charCodeAt(0))
  const key = await crypto.subtle.importKey(
    'raw', keyData, { name: 'HMAC', hash: 'SHA-256' }, false, ['verify']
  )
  const msgData = new TextEncoder().encode(signedContent)

  // svix-signature may contain multiple comma-separated values
  for (const sig of svixSignature.split(' ')) {
    const prefix = 'v1,'
    if (!sig.startsWith(prefix)) continue
    const sigBytes = Uint8Array.from(atob(sig.slice(prefix.length)), c => c.charCodeAt(0))
    const valid = await crypto.subtle.verify('HMAC', key, sigBytes, msgData)
    if (valid) return JSON.parse(body)
  }
  throw new Error('invalid webhook signature')
}

Retries and dead letters

Failed deliveries are retried with exponential backoff. After the maximum retry count, the message is written to the dead-letter store in D1 for manual inspection.
Delivery is decoupled from the authentication path through Cloudflare Queues. A slow or unavailable endpoint does not affect login latency.
Use the svix-id header to deduplicate deliveries on your end. Retries carry the same svix-id as the original attempt.

flowchart LR
  XID --> Queue
  Queue -->|HTTPS| Endpoint
  Endpoint -->|2xx| ACK
  Endpoint -->|non-2xx| Retry
  Retry --> Queue
  Retry -->|max_retries| dlq["D1 DLQ"]

Manual replay

Use POST /v1/webhooks/:endpointId/replay to replay events by message ID or time range. Replayed events carry fresh svix-id values but preserve the original type and data.

# Replay events from the last hour
curl -X POST https://xid.dev/v1/webhooks/whe_xxx/replay \
  -H 'Authorization: Bearer sk_live_xxx' \
  -H 'Content-Type: application/json' \
  -d '{ "since": "2024-01-01T00:00:00Z", "until": "2024-01-01T01:00:00Z" }'

Events API

In addition to push webhooks, XID exposes an ordered, immutable event stream with cursor pagination at GET /v1/events. Pull the stream to build reliable synchronization without missing events between webhook retries.

curl 'https://xid.dev/v1/events?limit=100&after=evt_xxx' \
  -H 'Authorization: Bearer sk_live_xxx'