Google Chrome allows TLS MITM proxies to override HPKP settings (which is not without controversy):<p><i>We deem this acceptable because the proxy or MITM can only be effective if the client machine has already been configured to trust the proxy’s issuing certificate — that is, the client is already under the control of the person who controls the proxy (e.g. the enterprise’s IT administrator). If the client does not trust the private trust anchor, the proxy’s attempt to mediate the connection will fail as it should.</i><p><a href="https:&#x2F;&#x2F;www.chromium.org&#x2F;Home&#x2F;chromium-security&#x2F;security-faq#TOC-How-does-key-pinning-interact-with-local-proxies-and-filters-" rel="nofollow">https:&#x2F;&#x2F;www.chromium.org&#x2F;Home&#x2F;chromium-security&#x2F;security-faq...</a><p><a href="https:&#x2F;&#x2F;code.google.com&#x2F;p&#x2F;chromium&#x2F;issues&#x2F;detail?id=561646" rel="nofollow">https:&#x2F;&#x2F;code.google.com&#x2F;p&#x2F;chromium&#x2F;issues&#x2F;detail?id=561646</a>