SMS OTP and Mobile Verification API

We take the SMS headache out of mobile verification and one-time passwords (OTPs).

Use this API to verify user identity (mobile verification) or possession of a device (OTP/two-factor authentication):

1. Send an SMS verification code - generate a secret code and send it to the user's phone.
2. Verify the code - check the user's input against the code you just sent.

Since its creation, Textbelt has sent over 3 million texts and OTPs from the command line and other software clients!

$ curl -X POST https://textbelt.com/otp/generate \
       --data-urlencode phone='5557727420' \
       --data-urlencode userid[email protected]' \
       -d key=example_otp_key

import requests
requests.post('https://textbelt.com/otp/generate', {
  'phone': '5557727420',
  'userid': [email protected]',
  'key': 'example_otp_key',
})

require 'net/http'
require 'uri'

uri = URI.parse("https://textbelt.com/otp/generate")
Net::HTTP.post_form(uri, {
  :phone => '5557727420',
  :userid => [email protected]',
  :key => 'example_otp_key',
})

var request = require('request');
request('https://textbelt.com/otp/generate', {
  body: {
    phone: '5557727420',
    userid: [email protected]',
    key: 'example_otp_key',
  },
})

using System;
using System.Collections.Specialized;
using System.Net;

using (WebClient client = new WebClient())
{
  byte[] response = client.UploadValues("http://textbelt.com/text", new NameValueCollection() {
    { "phone", "5557727420" },
    { "userid", "[email protected]" },
    { "key", "example_otp_key" },
  });

  string result = System.Text.Encoding.UTF8.GetString(response);
}

$ch = curl_init('https://textbelt.com/otp/generate');
$data = array(
  'phone': '5557727420',
  'userid': [email protected]',
  'key': 'example_otp_key',
);

curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($data));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$response = curl_exec($ch);
curl_close($ch);

Request.Post("https://textbelt.com/otp/generate").bodyForm(Form.form()
  .add("phone", "5557727420")
  .add("userid", "[email protected]")
  .add("key", "example_otp_key")
  .build())
 .execute().returnContent();

Response Details

OTP generation (/otp/generate)

{"success": true, "textId": "1234", "quotaRemaining": 70, "otp": "672383"}

Check success to determine whether the OTP was sent to the user. This means the user was sent a text containing an OTP. By default the message format is: "Your verification code is 672 383".

There are a few parameters you can add to your request:

• message will replace the default OTP message. Use the $OTP variable to include the OTP.
• lifetime will determine how many seconds the OTP is valid for. If you set lifetime to 240, the OTP will be valid for 240 seconds or 4 minutes.

$ curl -X POST https://textbelt.com/otp/generate \
       --data-urlencode phone='5557727420' \
       --data-urlencode [email protected]' \
       --data-urlencode message='Nuclear launch code: $OTP! Use it to login.' \
       -d lifetime=120 \
       -d key=example_otp_key

Example out-of-quota or invalid key response from /otp/generate:

{"success": false, "quotaRemaining": 0, "otp": ""}

OTP verification (/otp/verify)

Here's an example valid OTP response from /otp/verify. Check isValidOtp to decide whether the OTP has been approved:

{"success": true, "isValidOtp": true}

Example response for an invalid OTP. Note that "success" indicates a successful response, not a successful OTP:

{"success": true, "isValidOtp": false}

Get started

OTP keys are the same as normal Textbelt keys. This means you can mix and match your quota to send OTPs and normal text messages.

You're ready to go! Fill out the form below to generate a key.

Get in touch

Any questions? Email [email protected], text +1 (650) 332-4607, or read the FAQ.