Let’s Encrypt has been running a Certificate Transparency (CT) log since 2019 as part of our commitment to keeping the Web PKI ecosystem healthy. CT logs have become important infrastructure for an encrypted Web 1, but have a well-deserved reputation for being difficult to operate at high levels of trust: Only 6 organizations run logs that are currently considered to be “qualified.” 2
Our Oak log is the only qualified CT log that runs on an entirely open source stack 3.