Certificates For A Domain Screensaver
The Certificate Transparency screensaver lists certificates issued for a domain, newest first, from the public transparency logs. Every publicly trusted certificate authority must log every certificate it issues to these append-only logs, precisely so that a mis-issued certificate cannot stay secret. Point it at your own domain and it becomes a monitoring tool. It runs in the browser with nothing to install; press ESC to exit.
How the Certificates For A Domain screensaver works
The saver reads SSLMate's Cert Spotter API, which serves the public CT logs key-free.
No account and no key: the request goes straight from your browser, or from this site's own refreshed copy of the feed where the source does not allow browser access.
Values are drawn on a canvas that resizes with the window, so it works on a laptop or a wall display.
If the source is unreachable the saver says so on screen rather than showing stale numbers as though they were current.
A worked example
Each row shows the first hostname on the certificate, the issuing authority, how many additional names the certificate covers, and the date it became valid. A large site's wildcard certificate covers dozens of names at once. With ninety-day certificate lifetimes now the norm, a busy domain reissues constantly, and the dates make that rhythm visible.
Settings & tips
- Accent and Background recolour the display without changing the data.
- Add it to a Multi-view grid to watch it alongside other live savers.
- Press ESC at any time to leave fullscreen.
Frequently asked questions
- What is certificate transparency?
- A public, append-only log of every certificate issued by a trusted authority. It exists so that mis-issuance can be detected: if somebody obtains a certificate for your domain, it must appear in these logs, where anyone can see it.
- Can I watch my own domain?
- Yes. Change the domain setting and it queries the logs for that name and its subdomains. Seeing an issuance you did not request is exactly the signal the log system was built to provide.
- Is this real data?
- Yes. It comes from SSLMate's Cert Spotter API, which serves the public CT logs key-free. Nothing is invented or simulated, and if the source cannot be reached the saver reports that instead of drawing something plausible.
- Does it cost anything or need an account?
- No. Every screensaver here is free, runs in the browser and needs no sign-up. This one uses a public API that requires no key.