Ran this at my address and it said database last updated in 2017 :( But the site is cool!!!

Available in which countries?

I was hoping that, since it takes terrain into account, it might be more accurate than other sites I've used. I'm in a bit of a valley and get zero channels. Everyone near me that watches OTA has a antenna elevated to at least 20 feet. This lists 5 channels as "green."

It also seems to use licensed ERP rather than actual ERP. There is a VHF station near me licensed for 300W that only broadcasts at 100W ERP; this site lists it as 300W.

"can receive" has a different meaning with encrypted ATSC 3.0 signals. My HD Homerun TV tuner happily displays ATSC 1.0 signals and also the single unencrypted ATSC 3.0 signal from PBS. The rest of them are infected with Widevine DRM and unwatchable on a network tuner. Obviously DVR functionality is disabled as well.

Public airwaves carrying TV channels that can only be viewed with an Internet connection to deliver a decryption key is one of the dumbest things I have ever encountered. It is a blatant privatization of a public resource, so naturally I expect the current administration's FCC to bless it despite lawsuits and public comments ahead of their final rulemaking.

Check out Lon Seidman's coverage of the issue for more information. https://blog.lon.tv/

Why does this tvfool.com site seem so determined to have me install browser plugins? No, thank you...

Is there not some official site for this?

e.g. in the uk we have https://www.freeview.co.uk/ which has a reception checker and full tv guide