Awesome
Certificate Transparency Subdomains
An hourly updated list of subdomains gathered from certificate transparency logs.
How it works
We use certstream to subscribe to the certificate transparency log stream. When an update is broadcasted, the domain is parsed and all subdomains inserted into our database.
A second script exports the top 100/1000/10,000/100,000 observered subdomains and pushes them into this repository on an hourly basis.