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If you want to send OTP codes, use the Verification API.Contrary to the Transactional API, the Verification API provides full access to our multi-channel system, gives access to lower SMS rates via our arbitrage system and protects verifications with our anti-fraud solution.

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Multi-channel delivery

The Transactional API supports sending messages across multiple channels including SMS and WhatsApp. When your template is configured for WhatsApp, messages will automatically be sent via WhatsApp first, with intelligent fallback to SMS if WhatsApp delivery is unavailable. You can also explicitly specify your preferred delivery channel using the preferred_channel parameter to prioritize a specific channel.

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Region support

The Transactional API is available in a number of regions. To see the full list, check the Region Support Table. New regions are coming soon, based on demand.

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API

The Prelude v2 API is a REST API and uses standard HTTP features and statuses. The current URL is https://api.prelude.dev/v2.

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Authentication

To perform requests on the API, you need to provide a v2 API key in the Authorization header. You can create an API key in the Dashboard, under the API Keys section of the settings.
Example request
curl --request POST \
     --url 'https://api.prelude.dev/v2/*' \
     --header 'Accept: application/json' \
     --header 'Authorization: Bearer <API_KEY>'

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Errors

Prelude uses conventional HTTP statuses to indicate the success or failure of a request:
  • Codes in the 2xx range indicate success.
  • Codes in the 4xx range indicate an error that failed given the information provided (e.g. required parameter was omitted or an authentication failed).
  • Codes in the 5xx range indicate an error with Prelude's servers (these are rare).
The Prelude API returns errors using a JSON object in the response body with a machine-readable code and a human-readable message and a param field. See Errors for more details as well as a list of all possible error codes.
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