@matigo It’s in pretty active use. Here’s Chromium’s current list: https://cs.chromium.org/chromium/src/net/http/transportsecuritystate_static.json
Even in 2013, uptake was significant: https://garron.net/crypto/hsts/hsts-2013.pdf
(This has been around for a good while now.)
/@hazardwarning @joanna @joeo10