Send SMS from your own backend.

Authentication

Every request carries your API key as a bearer token — never your dashboard login, and a leaked API key can never be used to sign into the dashboard either.

Authorization: Bearer <publicKey>.<secret>

Send a message

Every mutating request requires an Idempotency-Key header — a value you generate yourself and reuse if you need to retry the same request. A repeated request with the same key returns the original result instead of sending a second message.

curl -X POST https://sendly.ng/api/v1/messages/send \
  -H "Authorization: Bearer <publicKey>.<secret>" \
  -H "Idempotency-Key: <a-unique-value-per-request>" \
  -H "Content-Type: application/json" \
  -d '{
    "channel": "sms",
    "senderId": "Sendly",
    "route": "TRANSACTIONAL",
    "recipient": "+2348012345678",
    "content": "Your OTP is 123456."
  }'

A successful send returns:

{
  "data": {
    "messageId": "clx1...",
    "status": "SUBMITTED"
  }
}

A rejected send (an unapproved Sender ID, an unsubscribed contact, insufficient wallet balance, or a validation error) returns a structured error instead of a bare status code, so your integration can show the real reason rather than a generic failure:

{
  "error": {
    "code": "SEND_FAILED",
    "message": "This Sender ID isn't approved with any active messaging provider yet."
  }
}

Rate limits

Limits apply per API key and per organization, and scale with your account tier — a rate-limited request returns 429 with a Retry-After header rather than failing silently. On the standard tier: 60 requests per minute per key, 120 per minute per organization.