How to Detect VPNs with JavaScript

Detecting VPN usage has become increasingly important for websites and applications looking to prevent fraud, ensure compliance, or manage content access. While no method is foolproof, certain techniques can help identify VPN connections. One primary method to detect VPNs is by checking the user's IP address against known VPN servers using an API service. This can be done using JavaScript by fetching data from the API and checking if the IP address is listed as a VPN server. Another way to detect VPN usage is by comparing the user's geolocation with their reported IP address, which can be done by fetching geolocation data from an API and comparing it to the IP address. DNS leak tests can also be performed by checking the DNS servers being used and comparing them to known public DNS servers. Behavioral analysis can also be used to detect VPN usage by tracking changes in geolocation or unusual access patterns. Combining these methods can provide a more comprehensive approach to detecting VPN usage. However, it's essential to remember that no method is infallible, and legitimate users might be affected by false positives. Legitimate users may be using VPNs for various reasons, and it's crucial to consider this when implementing VPN detection methods. False positives can be minimized by using multiple detection methods and analyzing the results. By understanding the different methods of detecting VPN usage, developers can create more effective solutions to prevent fraud and ensure compliance.