POST https://api.alert21.in/v1/sms/sendEndpoint
POST https://api.alert21.in/v1/sms/sendAuthentication
Authorization: Bearer <API_KEY>Request Body
{
"to": "919876543210",
"template_id": "1107161234567890123",
"variables": ["Amit", "2500", "TXN88991"]
}| Field | Type | Required | Description |
|---|---|---|---|
| to | string | Yes | Recipient in international/E.164-style numeric format expected by the enabled route |
| template_id | string | Yes | Approved template identifier mapped to the customer account |
| variables | array of strings | Conditional | Ordered values inserted into template variable positions; send an empty array if the template has no variables |
Recommended Success Response
{
"success": true,
"data": {
"message_id": "AL21SMS260824001234",
"status": "queued",
"to": "919876543210",
"credits_used": 1,
"submitted_at": "2026-08-24T14:00:00+05:30"
}
}Validation Rules
- API key must be active and authorized for SMS.
- Recipient format must be valid for the destination.
- Template must belong to or be authorized for the customer account.
- Template must be active.
- Variable count must match the approved template configuration.
- Message category and destination must be permitted.
- Sufficient wallet/credit entitlement must exist where prepaid billing applies.
- Rate limits and abuse controls must pass.
Message Status Endpoint
GET https://api.alert21.in/v1/sms/{message_id}queued, processing, submitted, sent, delivered, failed, rejected, expired, undelivered, cancelled.
Production Integration Recommendations
- Treat a successful API response as acceptance, not final delivery.
- Use signed webhooks as the primary delivery-status mechanism.
- Use the status API for reconciliation.
- Never infer payment success or other business success from SMS delivery.
- Use idempotency keys for retry-sensitive events.
- Do not expose API keys in client-side code.
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