Free Hex Decode API Endpoint

Call the free hex decode API endpoint

Post the hex under a data key and ask for text:

curl -X POST https://aisenseapi.com/services/v1/hex_decode \
  -H "Content-Type: application/json" \
  -H "Accept: text/plain" \
  -d '{"data": "68656C6C6F"}'

hello

The other way is the hex encode API endpoint.

Three response shapes, one Accept header

Decoded bytes can be text, JSON or anything else, so the endpoint answers exactly as the Base64 decode API endpoint does, chosen by the Accept header:

Accept header sent	Response
text/plain	`text/plain; charset=utf-8`, the decoded text as the whole body
application/json	`{"type": "json", "decoded_data": ...}` when the bytes are JSON, otherwise `{"type": "binary", "encoding": "base64", "decoded_data": "..."}`
application/octet-stream, the wildcard or no header	`application/octet-stream`, an attachment named decoded_data.bin
anything else	HTTP 406 with a fix

curl -X POST https://aisenseapi.com/services/v1/hex_decode \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -d '{"data": "7b226f6b223a747275657d"}'

{"type":"json","decoded_data":{"ok":true}}

Sending the input

The digits 0-9 and a-f, in either case. A leading 0x and spaces, tabs and line breaks between the digits are allowed, so a hex dump can be pasted as it is. The count of digits has to be even, two for every byte.

Send the data as {"data": "..."} with Content-Type: application/json, or as the raw request body with any other content type. The raw body takes binary data as it is: curl --data-binary @file.bin -H "Content-Type: application/octet-stream".

Errors

Status	error	When
400	No data to decode.	No `data` string and no body
400	Invalid hex input.	An odd count of digits, or a character that is not hex
406	Unsupported Accept header.	An Accept header the endpoint cannot answer
413	Data over 1 MiB.	More than 1 MiB in one request

Each refusal also carries fix, a sentence saying what to send instead.

Common uses

Read a hex dump

Turn the hex a log, a debugger or a packet capture shows back into the text or file it was.

Digests and keys as bytes

Get the raw bytes of a key or a digest written in hex, to hand on to something that wants bytes.

Device payloads

Many sensors and radio networks deliver their readings as hex; decode them before parsing.

Privacy and limits

Nothing is stored. The hex decode answer is worked out while the request is open and the data is gone with it. The access log records the path and the status, not the body.

The base URL is https://aisenseapi.com/services/v1. There is no key, no account and no sign-up step. One request carries at most 1 MiB of data, and the service-wide limit is 5000 requests per IP address per day. Every endpoint in the collection is listed on the Free public REST APIs reference, and the encodings side by side on Encoding APIs.