Idempotency - PulseSend

A request can time out after PulseSend has already accepted it. Retrying blindly would send the email twice. To retry safely, add an Idempotency-Key header:

curl https://pulse-send.jiordiviera.me/api/v1/emails \
  -H "Authorization: Bearer $PULSESEND_API_KEY" \
  -H "Idempotency-Key: signup-otp-8f3a2c" \
  -H "Content-Type: application/json" \
  -d '{ "from": "...", "to": "...", "subject": "...", "html": "..." }'

How it works

The first request with a given key runs normally.
Any repeat within 24 hours returns the original response, with the header Idempotent-Replayed: true. Nothing is sent again.
Keys are scoped to the API key that sent them.

Pick a key that identifies the intent, not the attempt: an order ID, a user ID plus a purpose, or a UUID you generate once and reuse on retries.

Conflicts

Situation	Response
Same key, different body	`409` `idempotency_key_reused`
Same key while the first request is still running	`409` `idempotency_in_progress`. Wait and retry.
Key longer than 255 characters	`422` `idempotency_key_too_long`

Responses with a 5xx status aren’t stored, so retrying them with the same key runs the request again.