ExpressVPN has partnered with the Internet Watch Foundation to introduce OpenBoundary, a tool designed to restrict access to domains containing verified child sexual abuse material without compromising user privacy. The open-source technology uses simple DNS controls to block illegal content. ExpressVPN plans to implement it across its services, including CyberGhost VPN and Private Internet Access.
ExpressVPN announced on Wednesday its collaboration with the Internet Watch Foundation (IWF) to launch OpenBoundary, a new technology aimed at enabling network operators to safely and transparently restrict access to verified criminal domains hosting child sexual abuse material (CSAM).
OpenBoundary works by blocking access to all CSAM domains identified and verified by the IWF. As a virtual private network (VPN) provider, ExpressVPN emphasizes that while VPNs hide user identity and location to protect privacy, they can sometimes be misused to access illegal content anonymously. The tool prevents users from reaching blocked domains without breaking encryption, inspecting traffic, or monitoring activity.
"OpenBoundary isn't a breakthrough in cryptography. It's a simple, well-scoped DNS control used to block access to known child sexual abuse material sites," said Peter Membrey, chief research officer at ExpressVPN, in a press release. "No broken encryption. No traffic inspection. No monitoring. It's deliberately straightforward, because privacy systems lose trust when they become opaque."
ExpressVPN will deploy OpenBoundary in its own services, including CyberGhost VPN and Private Internet Access, and has made the tool open-source to encourage adoption by other VPN providers, internet service providers (ISPs), and cloud platforms. This initiative is part of ExpressVPN's broader "Not on My Network" effort to enhance both privacy and protection in digital environments.
Membrey added, "That's far bigger than any single technical measure. What we are saying is that privacy infrastructure does not have to carry everything indiscriminately. With clear boundaries and careful engineering, it's possible to act without weakening the protections millions of people rely on." The company positions OpenBoundary as a step toward a safer online space for families and children, while maintaining its commitment to user privacy.