This is great. Believe it or not, when I purchased my home last year, when going through underwriting for my mortgage, I had to sign a message of my bitcoin address with my ColdCard to prove that I owned the bitcoin for more than 60 days to ensure my funds were "seasoned." I had to point them to the website verifybitcoinmessage.com (since it was one of the few supporting BECH32 addresses) so they could verify it themselves and I explained to them how to do it. But frankly, that website doesn't seem legitimate to anyone not knowing what they're doing, so it didn't really instill confidence.

Checkmsg.org looks a lot more professional and I wish it was around a year ago. Thankfully everything cleared underwriting, but it wasn't without me pressing really hard and a lot of explanation about how bitcoin works to get them to accept it. At the end of the day I told them that bitcoin message verification is a lot more concrete proof of funds than any PDF statement that could be tampered with that they'd receive showing proof of funds from any other traditional financial institution.

I'll be sure to use checkmsg.org going forward if I never need to.