How to Build a Simple Phone Number Validator In JavaScript

by | Jul 31, 2023

Data security is one of the most important issues businesses have to deal with today. Before sending confidential and important data to their users, businesses should ensure that the user requesting the data is correct. Businesses have recently performed phone number validation before sending important data to users. The simplest way to provide phone number validation is to use the phone number validator tool today.

Phone number validator tools that provide phone number validation services provide businesses with information about whether their phone numbers are valid. In fact, many APIs today check whether the phone data is valid and provide a lot of detailed information about the phone number. In this article, we will discuss the use cases of a phone validator tool. Then we will introduce today’s most popular phone number validator tool and develop a web application with this API.

What are the Use Cases of the Phone Number Validation Tool?

Businesses often use a phone validator tool to validate personal and business numbers. But these tools have many use cases. Some of these use cases are as follows:

  • User Registration: Businesses may require phone number verification to enroll new users with a website or app. This allows users to add a real and valid phone number to the system. This prevents the creation of fake accounts.
  • Two-Factor Authentication: Two-factor authentication provides an additional layer of security when users log into business applications or access sensitive information. With a phone validator tool, businesses can minimize errors in two-factor authentication processes. This is because, with this tool, businesses have only added valid numbers to their systems.
  • Fraud Prevention: Phone number verification tools can be used for fraud prevention to prevent the creation of fake accounts or malicious use. This is a use that directly increases data security.
  • Keeping the Database Clean: With a phone number validation tool, businesses can determine whether their customers’ phone data is correct. Businesses may not save their customers who share invalid phone number information in the database. In this way, invalid data is not included in the ‘customer’ table that businesses keep in a database. This is also one of the most efficient ways to use storage space in the database.

Discover the top 7 reliable phone number validation tool!

The numverify API: Invalid Phone Numbers Detector

home page of the numverify phone number validator api

The numverify offers today’s best API for phone number validation. It can validate phone numbers for 232 countries in the world.

It performs phone validation processes in 232 countries in just seconds. The numverify API processes the requested phone numbers in real-time and cross-checks them with the latest international numbering plan database.

The comprehensive API provided by the numverify can be easily integrated into all programming languages today. In addition, the current documentation provided by it contains sample integration codes of this API to programming languages such as PHP and JavaScript.

Finally, this API has multiple affordable subscription plans. It even has a free plan. With that free plan, it offers its users a monthly request limit of 100 requests. In addition, the first of the paid packages is only $14.99 per month for 5,000 requests.

What Fields Does the numverify API Provide?

The numverify API doesn’t just check if a phone number is valid. If the phone number is valid, detailed information about this phone number is provided. The information it provides includes information such as country code, location, carrier, and line type. The sample JSON response provided by this API for a valid phone number is as follows.

json response of the numverify api

Building a Simple Phone Number Verification Web Application

Under this header, we will develop a number verification web application using the numverify API. In this web application, we will use HTML, CSS, JavaScript, and Bootstrap. The general flow of the application will start with the user entering the phone number and country code information from the interface. Then we will send this information to the numverify API with the JavaScript code and print the incoming response on the same page.

Before we start developing the application, we need to obtain an API key to use the API. To obtain the API key, we will sign up for one of the flexible and affordable subscription plans offered by numverify.

Sign up free - Numverify phone number verification API

After obtaining the API key, we can start developing our application. For this, let’s open a file named ‘phone-number-verification-with-the-numverify.html’ in the file path where we aim to develop the application. Then, let’s put the following codes in this file that we opened.

<!DOCTYPE html>
<html lang="en">

    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Phone Number Verification</title>
    <link rel="stylesheet" href="">
        body {
            padding: 20px;

        h1 {
            margin-bottom: 20px;

        .container {
            max-width: 600px;

        .table {
            background-color: #f8f9fa;
            border-radius: 10px;
            overflow: hidden;

        .table th,
        .table td {
            padding: 12px 15px;
            border-bottom: 1px solid #dee2e6;

        .table th {
            background-color: #343a40;
            color: #fff;
            font-weight: 500;

        .table td {
            background-color: #fff;
            color: #333;

        .table tbody tr:hover {
            background-color: #f2f2f2;

    <div class="container">
        <h1>Phone Number Verification</h1>
        <form id="validationForm">
            <div class="form-group">
                <label for="countryCode">Country Code:</label>
                <select class="form-control" id="countryCode" required>
                    <option value="">Select Country Code</option>
                    <option value="US">United States</option>
                    <option value="GB">United Kingdom</option>
                    <option value="DE">Germany</option>
                    <option value="FR">France</option>
                    <option value="JP">Japan</option>
            <div class="form-group">
                <label for="phoneNumber">Phone Number:</label>
                <input type="text" class="form-control" id="phoneNumber" required>
            <button type="submit" class="btn btn-primary">Validate</button>
        <div id="resultTable"></div>

        document.getElementById('validationForm').addEventListener('submit', function (event) {

            var countryCode = document.getElementById('countryCode').value;
            var phoneNumber = document.getElementById('phoneNumber').value;

            var url = '' +
                countryCode + '&number=' + phoneNumber;

                .then(function (response) {
                    return response.json();
                .then(function (data) {
                .catch(function (error) {
                    console.log('Error:', error);

        function displayResult(data) {
            var resultTable = document.getElementById('resultTable');
            resultTable.innerHTML = '';

            if (data.valid) {
                var table = document.createElement('table');
                table.className = 'table';
                var tbody = document.createElement('tbody');

                var row1 = document.createElement('tr');
                var row2 = document.createElement('tr');
                var row3 = document.createElement('tr');
                var row4 = document.createElement('tr');
                var row5 = document.createElement('tr');
                var row6 = document.createElement('tr');
                var row7 = document.createElement('tr');
                var row8 = document.createElement('tr');

                var cell1 = document.createElement('th');
                cell1.textContent = 'Valid';
                var cell2 = document.createElement('td');
                cell2.textContent = data.valid;

                var cell3 = document.createElement('th');
                cell3.textContent = 'Local Format';
                var cell4 = document.createElement('td');
                cell4.textContent = data.local_format;

                var cell5 = document.createElement('th');
                cell5.textContent = 'International Format';
                var cell6 = document.createElement('td');
                cell6.textContent = data.international_format;

                var cell7 = document.createElement('th');
                cell7.textContent = 'Country Code';
                var cell8 = document.createElement('td');
                cell8.textContent = data.country_code;

                var cell9 = document.createElement('th');
                cell9.textContent = 'Country Name';
                var cell10 = document.createElement('td');
                cell10.textContent = data.country_name;

                var cell11 = document.createElement('th');
                cell11.textContent = 'Location';
                var cell12 = document.createElement('td');
                cell12.textContent = data.location;

                var cell13 = document.createElement('th');
                cell13.textContent = 'Carrier';
                var cell14 = document.createElement('td');
                cell14.textContent = data.carrier;

                var cell15 = document.createElement('th');
                cell15.textContent = 'Line Type';
                var cell16 = document.createElement('td');
                cell16.textContent = data.line_type;



            } else {
                resultTable.textContent = 'Invalid phone number.';

Let’s paste our own API key into the ‘YOUR-API-KEY’ field in our code piece and start the application. When we start the application, the following default page will welcome us.

default page of the number verification app

After filling in the phone number and country code fields on this page and pressing the ‘Validate’ button, the inputs we enter will be sent to the numverify API, and its response will be printed on the screen as below.

result table of the number verification app


To sum up, number validation is absolutely used in basic security steps in many businesses today. Thus, businesses send confidential and sensitive data to users they are sure of and do not allow data vulnerabilities to occur. There are many APIs available today that provide phone number validation. These APIs support hundreds of phone numbers globally, providing great convenience to businesses with international users.

Try the best number verification API of recent times, in addition to number validation information and get a lot of valuable information.


Q: Does the numverify Do Bulk Phone Number Validation?

A: No, it does not. The numverify API does not support the phone number verification service it offers to users with bulk data. Instead, it receives a single phone number information with the endpoint it provides and presents the information of this phone number.

Q: What are the Some Common Use Cases of the Phone Number Validator API?

A: There are many use cases where businesses and developers use a phone validator API. The most popular of these use cases are as follows:

  • User Registration
  • Two-Factor Authentication
  • Fraud Prevention

Q: What are the Advantages of Validating Phone Numbers?

A: Verifying phone numbers has great benefits for developers and businesses. Some of these advantages are as follows:

  • Ensures Accuracy of Customer Data
  • Increases Communication Efficiency
  • Prevents Fraud
  • Provides Personal Data Security
  • Improves Customer Experience
  • Reduces Spam and Spam

Q: What are the Best Phone Number Verification APIs to Use in My Projects?

A: There are many number verification APIs today, but only some of them offer a reliable service. Some of the APIs that provide a reliable number validation service to their users are:

  • Numverify
  • Abstract API
  • Numlookup API
  • Neutrino
  • Mocean API
  • Nexmo Verify API

Q: How Does a Phone Number Validator Tool Work?

A: Phone number verification tools usually check the accuracy of phone numbers by following certain steps. First, it checks that the incoming phone number is in the correct format, that is, it is the correct length, and has a valid country code and region code. It then compares the phone number to a specific database or service provider, checking that the number represents a real and active line. This is usually done by calling the API or using various verification methods. Finally, the number is determined to be valid or invalid, and relevant information (country code, region code, operator, etc.) is provided.

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