Some pointers for you: - The Perspectives project (http://perspectives-project.org/ http://perspectives-project.org/) aimed to deploy a range of servers (calle

Some pointers for you: - The Perspectives project (http://perspectives-project.org/ http://perspectives-project.org/) aimed to deploy a range of servers (called notaries), through which you can ask "What cert do you see for https://google.com https://google.com ?", and compare the response. The idea was that certificates should be mostly the same wherever you're asking from. - Convergence (https://en.wikipedia.org/wiki/Convergence_(SSL) https://en.wikipedia.org/wiki/Convergence_(SSL)) is a fork of the same idea. The issue with both of them is, of course, privacy leaks, which the latest version of convergence (https://github.com/mk-fg/convergence#changes-from-upstream https://github.com/mk-fg/convergence#changes-from-upstream) solves with a custom onion routing. The other problem I see is that it still (in the current form) requires the user to manually edit the notaries list. So, it does exist, maybe it's just lacking publicity ?