Software Design

Direct S3 Uploads via Presigned URLs

UML Sequence Diagrams · made in Skemio

Sequence diagram showing Browser requesting presigned URL from App API, uploading directly to S3, and S3 notifying Event Worker.
Sequence diagram showing Browser requesting presigned URL from App API, uploading directly to S3, and S3 notifying Event Worker.
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What it shows

  • Backend generates cryptographically signed upload URLs in under 10ms
  • Browsers stream raw binary payloads directly to object storage targets
  • Storage events trigger asynchronous background processing without API lag

The takeaway

Keep large payload I/O off backend app servers by delegating uploads directly to object storage.

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