The testing was done independently - I tested both affiliate and non-affiliate services equally using the same methodology. Services like NordVPN, Surfshark, ExpressVPN, Mullvad were all tested (mix of affiliate and non-affiliate).

PureVPN and IPVanish are mentioned because they passed all leak tests in my testing. Proxy-Seller is mentioned because it represents the category of "premium proxies" vs "free proxies" (which all failed).

The testing tool itself (examineip.com/vpn-leak-test) has zero affiliate links it's completely free and independent.