Certificate transparency is superb improvement to HTTPS certificate security on the web that's great for users and businesses, but on Android it creates a huge problem for the many developer tools like HTTP Toolkitopens in a new tab which install trusted system certificates into Android to intercept & debug app traffic. You can install your own CA certificates to intercept HTTPS traffic on Android, but intercepting any interesting traffic from an app that isn't explicitly opting-in to interception requires you to put your certificate into the 'system' store, not just the normal 'user' store.