The _pxhd cookie is a state-tracking token used by Human Security (formerly PerimeterX) within its bot-detection and anti-fraud protection platform. It typically stores cryptographically signed or encrypted data summarising previous verification outcomes (e.g., timestamps, counters, behavior sensors) so that subsequent requests from the same browser session can be evaluated more efficiently.

How it works

1. When a user first interacts with a site protected by Human Security, client-side sensors collect behavioural and environment signals (mouse movement, timing, browser APIs, etc).
2. Once initial verification succeeds, the system issues the _pxhd cookie containing the summary state.
3. On subsequent requests the cookie is sent back; the server uses it to decide faster whether the session appears human-like or automated. If the cookie is missing, invalid, or inconsistent, a full re-assessment (or challenge) may be triggered.
4. By caching verification state in _pxhd, the system blends security and performance by having fewer heavy checks while maintaining bot detection.

Relevance for Kameleo users

‍Since Kameleo is used for automation and browser-emulation, preserving a coherent cookie session and human-like behaviour is vital so that the _pxhd cookie remains valid and the protection system does not flag the session as automated. Ensuring consistent fingerprinting, naturally timed events, and stable cookies helps avoid triggering fresh challenges.

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