HTTP-Based Public Key Pinning (HPKP) was intended to allow websites to send an HTTP header that pins one or more of the public keys present in the site's certificate chain. It has very low adoption, and although it provides security against certificate misissuance, it also creates risks of denial of service and hostile pinning. See https://groups.google.com/a/chromium.org/d/msg/blink-dev/he9tr7p3rZ8/eNMwKPmUBAAJ for details.