#cs
This example reproduces the problem I encounter when sending a post request to an echo server.
Instead of being sent as text utf8, the data is transmitted base64 encoded.

Example:
json String: '{"firstName":"Jonathan","lastName":"Freeman","loginCount":4,"active": "yes","text":"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi vel volutpat nunc. Maecenas id tempus mi. Morbi ipsum enim, ultricies ac augue sit amet, ullamcorper finibus ex. Vestibulum vel posuere nibh, nec faucibus eros. Nam malesuada non lacus a suscipit. Nulla rhoncus tempus mi quis placerat. Curabitur commodo tincidunt justo quis sollicitudin."}'
server response: "data:application/octet-stream;base64,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"

How can I go about transmitting data in text format utf8?
Thanks in advance for the help.

In the zip file:
- CurlJsonPost.au3: this script
- Curl.au3: UDF by Ward (thank you!)
- data.json: json srting for command line test

Note: using Curl.exe with json string saved in a file utf8 encoded named data.json, works perfectly
To try with the command line tool:
- save data.json in curl\bin directory
- open cmd.exe and cd to curl\bin directory
- Enter the following command:
curl -H "Content-Type: application/json" --data @data.json https://httpbin.org/post

#ce
#Include "Curl.au3"

Global $_cURL_OutputBuffer

Local $sJson  = '{"firstName":"Jonathan","lastName":"Freeman","loginCount":4,"active": "yes","text":"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi vel volutpat nunc. Maecenas id tempus mi. Morbi ipsum enim, ultricies ac augue sit amet, ullamcorper finibus ex. Vestibulum vel posuere nibh, nec faucibus eros. Nam malesuada non lacus a suscipit. Nulla rhoncus tempus mi quis placerat. Curabitur commodo tincidunt justo quis sollicitudin."}'
Local $iRetCode, $sServerResponse

ConsoleWrite("=== Json post test ===" & @LF)
ConsoleWrite(StringFormat("Retcode: %s - %s", $iRetCode, Curl_Easy_strerror($iRetCode)) & @LF)
ConsoleWrite("Data returned from server" & @LF & @LF)
$sServerResponse = JsonPost_Test($sJson, $iRetCode)
ConsoleWrite($sServerResponse & @LF)


Func JsonPost_Test($sJson, ByRef $iRetCode)

	; Init Easy Curl Interface e set url (echo service)
	Local $oCurl = Curl_Easy_Init()
	curl_easy_setopt($oCurl, $CURLOPT_URL, "https://httpbin.org/post")

	; Set content type header
	Local $headers = curl_slist_append(0, "Content-Type: application/json")
	curl_easy_setopt($oCurl, $CURLOPT_HTTPHEADER, $headers)

	; Post fields & size
	Local $stString = DllStructCreate("char v[" & StringLen($sJson) & "]")
	DllStructSetData($stString, 1, $sJson)
	curl_easy_setopt($oCurl, $CURLOPT_POSTFIELDS, DllStructGetPtr($stString))
	curl_easy_setopt($oCurl, $CURLOPT_POSTFIELDSIZE, StringLen($sJson))

	; Set callbac function to get server response back (see global var $_cURL_OutputBuffer)
	$hWriteFunc = DllCallbackRegister("WriteFunc_CallBack", "uint:cdecl", "ptr;uint;uint;ptr")
	curl_easy_setopt($oCurl, $CURLOPT_WRITEFUNCTION, DllCallbackGetPtr($hWriteFunc))

	; Ignore ssl certificates check
	curl_easy_setopt($oCurl, $CURLOPT_SSL_VERIFYPEER, 0)
	curl_easy_setopt($oCurl, $CURLOPT_SSL_VERIFYHOST, 0)

	; Execute the post request
	$iRetCode = curl_easy_perform($oCurl)

	; Set return trasfer & clear output buffer global var
	Local $sReturnTransfer = $_cURL_OutputBuffer
	$_cURL_OutputBuffer = ""

	Return SetError(0, 0, $sReturnTransfer)
EndFunc

Func WriteFunc_CallBack($ptr,$nSize,$nMemb,$pStream)
	Local $vData = DllStructCreate ("byte[" & $nSize*$nMemb & "]",$ptr)
	$_cURL_OutputBuffer &= BinaryToString(DllStructGetData($vData,1))
	Return $nSize*$nMemb
EndFunc