SPARK

Webhooks

Receive an HTTPS POST when someone new joins your waitlist. SPARK records each attempt (success or failure), HTTP status, duration, and time (shown in your local timezone below).

Waitlist webhooks

Deliveries (all time)

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Success

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Failure

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Last delivery (local)

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Must use https. Leave empty to disable delivery until you set a URL.

If set, requests include X-Spark-Signature: sha256=<hex> (HMAC-SHA256 of the raw JSON body). Leave blank when saving to keep the current secret.

Event payload (request body)

Method POST, header Content-Type: application/json. Your endpoint should respond with any 2xx status quickly; response bodies are ignored.

{
  "event": "waitlist.subscriber.created",
  "app_id": "550e8400-e29b-41d4-a716-446655440000",
  "subscriber": {
    "id": "…",
    "app_id": "550e8400-e29b-41d4-a716-446655440000",
    "email": "signup@example.com",
    "created_at": "2026-03-29T12:00:00Z",
    "referrer": "https://…",
    "referrer_host": "example.com",
    "page_url": "https://…",
    "user_agent": "…",
    "accept_language": "en-US",
    "utm_source": "…",
    "utm_medium": "…",
    "utm_campaign": "…",
    "utm_term": "…",
    "utm_content": "…"
  }
}

Optional fields on subscriber are omitted when empty. This is the same shape as subscriber objects from your public API, with RFC3339 created_at.

Recent deliveries

Newest first. Failed rows include HTTP status or transport error text.

Time (local) Status HTTP ms Subscriber