My tool from 2015 that publishes arbitrary text to the Bitcoin blockchain in such a way that this site (or strings -n 20 blk*.dat) can easily find and display that text.
Note: I haven't actually used that tool since forever, so I'm not sure it actually works right now... Possible that changes to the Bitcoin Core RPC calls broke it over the years.
strings -n 20 blk*.dat) can easily find and display that text.