Polly async needs an S3 bucket; Sume gives a status URL and webhook

Amazon Polly's asynchronous synthesis queues your text, then "uploads the resulting speech or speech marks stream directly to your (required) Amazon Simple Storage Service (Amazon S3) bucket" and can tell you through an optional SNS topic. It handles up to 100,000 billable characters. Sume TTS 1.0 needs no bucket: the job returns a status_url and result_url, and a webhook_url gets a signed terminal event.

Polly's behavior is from its long audio files page, read 2026-10-01; Sume's from the OpenAPI schema behind the API reference.

What do you set up on each side?

Polly needs cloud storage and permissions; Sume needs a URL.

What can the Sume webhook do and not do?

Delivery is terminal-only: job.completed, job.failed and job.canceled. There are no progress or partial callbacks, so keep status_url polling as a backup. The callback URL must be public HTTPS; localhost, private-network and non-HTTPS URLs are rejected.

Do I lose anything by dropping the bucket?

The page notes you can keep the Polly output encrypted in S3 with AES-256 under your own bucket policy. A Sume result is hosted by Sume instead. If your rules require the file to land in storage you own, copy it from the result URL after the job completes.

How do I submit with a webhook?

Sending a webhook URL without a mode selects webhook mode.

curl -X POST https://api.sume.com/v1/tts-1.0/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: article-9921" \
  -d '{
    "transcript": "Read this article aloud.",
    "avatar_handle": "@narrator",
    "webhook_url": "https://example.com/hooks/tts"
  }'