To get the hash from a URL:
curl -s "https://dagger-ui.vercel.app/api/favicon-hash?url=https://test.com" | jq .
To get the hash from a file:
curl -s -F "file=@some_file.ico" https://dagger-ui.vercel.app/api/favicon-hash?url=https://test.com-from-file | jq .