Service quotes about #HSTS/#HPKP from http://blog.en.elevenpaths.com/2017/12/breaking-out-hsts-and-hpkp-on-firefox.html… Firefox: size limit 1024 entries + website scoring -> you can kick sites out of the list Chrome/ium: unlimited JSON file -> you can DDOS it by filling it >= 500MB IE/Edge: completly broken -> seems to store sth. but only applies HSTS to big websites Test yourself: https://www.cloudpinning.com/