How to Detect VPNs with JavaScript

In our increasingly connected world, VPNs (Virtual Private Networks) offer both advantages and challenges. While they help users maintain privacy and security, they can also be used for malicious purposes.

We’ll dive into how you can implement VPN detection in your web applications using JavaScript and the fetch API. You can use any API you want.

Why VPN Detection Matters

Before we jump into the code, let’s explore why detecting VPNs is important:

• Geographic Restrictions: If your service is region-specific, VPNs can bypass these limits.
• Fraud Prevention: VPNs can obscure a user’s true location, making it easier for malicious actors to commit fraud.
• Bots: Bots will sometime use thos.

Detecting VPNs ensures that your application is used as intended and helps protect your business from potential risks.

Getting Started: The Essentials

To detect VPNs in JavaScript, we’ll use a third-party service like IPQuery.io. This service provides detailed information about IP addresses, including whether they’re linked to VPNs, proxies, or other anonymizing tools.

Step 1: Setting Up Your Environment

Let’s keep things simple with vanilla JavaScript. No need for external libraries—just the built-in fetch API, which lets us make HTTP requests and process responses.

Step 2: Making the API Call

Here’s how you can use the fetch API to check if an IP address is associated with a VPN:

async function detectVPN(ip) {
    const response = await fetch(`https://api.ipquery.io/${ip}`);
    const data = await response.json();

    if (data.risk.is_vpn) {
        console.log(`The IP address ${ip} is associated with a VPN.`);
    } else {
        console.log(`The IP address ${ip} is not associated with a VPN.`);
    }
}

detectVPN('1.1.1.1');

In this example, the detectVPN function sends a GET request to the IPQuery API, which returns detailed information about the IP address, including whether it’s linked to a VPN.

Step 3: Handling Bulk Requests

Need to check multiple IP addresses at once? IPQuery supports bulk lookups too:

async function detectVPNs(ips) {
    const response = await fetch(`https://api.ipquery.io/${ips.join(',')}`);
    const data = await response.json();

    data.forEach(ipInfo => {
        if (ipInfo.risk.is_vpn) {
            console.log(`The IP address ${ipInfo.ip} is associated with a VPN.`);
        } else {
            console.log(`The IP address ${ipInfo.ip} is not associated with a VPN.`);
        }
    });
}

// Example usage
detectVPNs(['1.1.1.1', '2.2.2.2']);

This function takes an array of IP addresses, sends a request to the API, and checks each one for VPN associations. It’s an efficient way to process multiple addresses simultaneously.

Step 4: Customizing the Response Format

Depending on your needs, you might want the response in different formats like JSON, XML, or YAML. You can easily specify the format with a query parameter:

async function detectVPN(ip, format = 'json') {
    const response = await fetch(`https://api.ipquery.io/${ip}?format=${format}`);
    const data = await response.text();  // Use .text() for non-JSON formats

    console.log(data);
}

detectVPN('1.1.1.1', 'xml');

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