How to send OTP by SMS

An OTP is a one-time code that confirms a user’s identity. Generate it in your backend, send it by SMS, and validate the submitted value. SMSGo handles delivery through Brazilian carriers; the setup takes about 5 minutes.

1. 1Create an account and get your SMSGo-keyCreate an account, receive 3 free SMS with no card, and copy the key under Account → API.
2. 2Install an SDKUse npm i @orynlabs/smsgo, pip install smsgo, or call the REST API with cURL.
3. 3Generate a random codeGenerate a random 6-digit number in your backend.
4. 4Send the code by SMSCall send or POST /v1/sms/send/single with an international phone number, code, and expiry.
5. 5Store and verify the codeStore it with an expiry tied to the user, compare the submitted value, limit attempts, and invalidate it after use.

Example code

import { SMSGo } from '@orynlabs/smsgo'

const smsgo = new SMSGo({ apiKey: process.env.SMSGO_KEY })

// 1. generate a 6-digit code
const code = String(Math.floor(100000 + Math.random() * 900000))

// 2. send it
await smsgo.send({
  phone: '+5511999990000',
  message: `Your SMSGo code is ${code}. Valid for 5 minutes.`,
})

// 3. store code with a TTL (for example, Redis) and compare it during verification

Frequently asked questions

How do I generate an OTP code?

Generate a random 6-digit number in your backend. You control generation, expiry, and verification; avoid predictable sequences.

What is the ideal expiry?

Five to ten minutes. State the expiry in the message.

How do I verify it?

Store it with an expiry, compare the submitted value, invalidate it after use, and limit attempts.

How much does it cost?

From R$0.07/SMS, prepaid, with no monthly fee.