Anthropic is tightening access to its AI tool Claude after Chinese companies found ways to use it despite a strict regional ban. The company blocks access from unsupported regions, including China, but some firms used overseas entities, internal networks, VPNs, and personal subscriptions to keep Claude available to engineers. Ant Financial gave some employees corporate Claude accounts through its intranet, linked to a Singapore-based entity. ByteDance also allowed engineers to pay for personal Claude subscriptions and seek reimbursement, with access routed through VPNs. These methods broke Anthropic’s terms of service but did not break US or Chinese law. Microsoft also sold API access to Chinese companies with Singapore entities. Anthropic said it ‘explicitly prohibits accessing or facilitating access to Claude in unsupported regions, including China’ and uses changing detection systems to find and ban accounts that break its rules. The company has also focused on ‘transfer station’ services that route requests from mainland China through overseas Claude accounts. China’s National Vulnerability Database said several Claude Code versions released between April and June can send user location and identity data to remote servers without clear user consent.