How to detect proxies via API to a website from a different location without the web server seeing your real IP address. This enables you to bypass country restrictions, defeat rate-limiting, execute a web page’s javascript and fetch data as it would be rendered in the browser. Proxies are valuable tools for fraudsters and hackers attempting to steal credit card numbers, passwords or other information that could be used against customers or the company itself.

To protect your online infrastructure, you should use a service like ours to detect whether or not a user is using a proxy/VPN. We serve millions of API requests a week and our customers include gaming communities, e-commerce websites, research universities & institutions, large financial institutions, law enforcement and other security organizations.

The most common way to detect a proxy via API is to check for certain HTTP headers that are typically added by proxy servers, such as X-Forwarded-For or Forwarded. However, some proxies do not add these headers and this method can be unreliable.

How to Check an IP Address for Fraud Risk

Another approach is to compare the device’s operating system advertised by the browser’s user agent to the actual OS that was used to make the connection. This is a reliable method but not perfect, as many fraudsters have found ways to spoof the OS.

You can also use a latency test, which measures the time to send a small amount of data. If the test fails, this is a good indication that a user is using a proxy or VPN.