Idempotency▾

Idempotency

Send Idempotency-Key so a retried POST cannot deliver the same message twice.

Any POST accepts an Idempotency-Key header. Repeating a request with the same key returns the original response instead of performing the action again. Keys are scoped to your account and retained for 24 hours.

cURL

curl -X POST https://api.sendport.tech/v1/messages \
  -H "Authorization: Bearer $SENDPORT_KEY" \
  -H "Idempotency-Key: 7f8b1c02-4d5e-4a91-b3e0-0c1a2b3c4d5e" \
  -H "Content-Type: application/json" \
  -d '{"to":"+201005550123","type":"text","text":{"body":"Hi"}}'

Use a UUID per logical action

Generate the key when the action is created — an order id plus event name works well — not per HTTP attempt, or the retry gets a fresh key and sends twice.

Situation	Result
Same key, same body	The original response, with `Idempotent-Replay: true`
Same key, different body	`409 idempotency_key_reused`
Key older than 24h	Treated as new

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