I created a dashboard to view some basic info about the TLS certificates that I manage for various websites, including days to expiration, Issuer, Issuer Common Name, and certificate common name. It's also useful for enterprise infrastructure if you have to manage lots of web server certificates as part of a security or ops team.

I use a node module to scrape the peer certificate info, and then dump it into a file that a web page picks up. It's not real-time, out of concern for too many people hitting or reloading the page and kicking off too many connection attempts at once.

An example is here: https://craine.gitlab.io/tls-dashboard/