Hexadecimal contents of a file

Utility to get a JSON object with the members "name", "size", "sha3-512" and "bytes_hex" for the corresponding properties of a file. The "sha3-512" member is a string containing the SHA-3 (512) hash of the file or false in case the hash algorithm is unavailable. The "bytes_hex" member is a string with the bytes of the file written in hexadecimal, its length is size✗2.

You can also call this utility from the command line. For example, using curl to get the JSON object for the file "file.xls" and save it to a file "file.json":

curl -F "f=@file.xls" https://jansson.net/apps/filehex/ -o "file.json"