The StartSSL certificate is included by default in Mozilla Firefox 2.x and higher, in Apple Mac OS X since version 10.5 (Leopard), all Microsoft operating systems since 24 September 2009,[10][11] and Opera since 27 July 2010.[12] Since Google Chrome, Apple Safari and Internet Explorer use the certificate store of the operating system, all major browsers include support for StartSSL certificates.
On 30 September 2016, during the investigation on WoSign, Apple announced that their software will not accept certificates issued by one of the WoSign certificates after 19 September 2016, and said they will take further action on WoSign/StartCom trust anchors as the investigation progresses.[5]
On 24 October 2016, Mozilla announced on its security blog that, following its discovery of the purchase of StartCom by another Certificate Authority called WoSign during its investigation on numerous issues with that CA, and that both have failed to disclose this transaction,[13] Mozilla will stop trusting certificates that are issued after 21 October 2016 starting with Firefox 51.[14] On 1 November 2016, Google announced that it too would stop trusting certificates issued after 21 October 2016 starting with Chrome 56.[15]