Amazon SNS

Svix can deliver webhooks directly to an Amazon SNS topic, without your customers having to set up any listener endpoint or write any glue code.

When Advanced Endpoint Types is enabled, your customers will see the option to use an SNS destination in the App Portal.

They will be able to configure the connection right in the App Portal:

• topicArn — the ARN of the SNS topic to publish to.
• region, accessKeyId, secretAccessKey — the AWS region and credentials used to authenticate.

Every webhook in the batch is published to the topic as a separate message.

Transformations

By default, all SNS Endpoints come bundled with the following transformation code.

/**
 * @param input - The input object
 * @param input.events - The array of webhooks in the batch. The number of webhooks in the batch is capped by the endpoint's batch size.
 * @param input.events[].payload - The message payload (string or JSON).
 * @param input.events[].eventType - The message event type (string).
 *
 * @returns Object containing the response.
 * @returns returns.messages - The array of SNS messages to send to the SNS topic.
 * @returns returns.messages[].payload - The content of the message (string).
 * @returns returns.messages[].subject - An optional subject of the message (string).
 */
function handler(input) {
  const messages = input.events.map((event) => ({
    payload: event,
  }));

  return {
    messages,
  };
}

input.events is the list of webhooks received by the endpoint, processed in batches.

Each entry in the returned messages array is published as a separate SNS message. The payload becomes the message body, and the optional subject becomes the SNS subject. By default, each webhook is published as its serialized JSON, with no subject.

For example, if the endpoint receives the following messages:

{
  "eventType": "user.created",
  "payload": "{\"email\": \"joe@enterprise.io\"}"
}

{
  "eventType": "user.login",
  "payload": "{\"id\": 12, \"timestamp\": \"2025-07-21T14:23:17.861Z\"}"
}

The default transformation code would publish two messages to your topic, with the following bodies.

{"payload":{"email":"joe@enterprise.io"},"eventType":"user.created"}

{"payload":{"id":12,"timestamp":"2025-07-21T14:23:17.861Z"},"eventType":"user.login"}

To control the message bodies, or to set a subject, return your own array of messages. Each message’s payload becomes the body of one SNS message, and subject is published as that message’s SNS subject.

function handler(input) {
  const messages = input.events.map((event) => ({
    payload: JSON.stringify(event.payload),
    subject: event.eventType
  }));

  return {
    messages,
  };
}

SNS accepts at most 10 messages per batch request, so larger batches are automatically split across multiple PublishBatch calls.