Php curl send json

Php curl send json

The PHP cURL is a library used for making HTTP requests. In order to use PHP cURL, you must have installed and enabled libcurl module for PHP on your system. In this tutorial, you will learn how to POST JSON data with PHP cURL requests. Basically, there are 4 steps involved to complete a cURL request using PHP.

  • curl_init — The first step is to initializes a new session of cURL and return a cURL handle to other functions.
  • curl_setopt — The second step is to set options for a cURL session handle. All these settings are very well explained at curl_setopt().
  • curl_exec — In third step it perform a cURL session based on above options set.
  • curl_close — The last step is to close a cURL session initialize by curl_init() and free all resources. Also deleted the cURL handle.

Let’s use the below sample code to create a POST request with PHP cURL.

The main thing is that the request must be a POST request with properly json-encoded data in the body. The headers must properly describe the post body.


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very helpful,
thank you

Is there a way to avoid the auto “Content-Type: application/x-www-form-urlencoded
” when using POST, I mean, I’m using the following code:
$ch = curl_init();
‘x-api-key: ‘.$gdxApiKey,
‘Authorization: Bearer ‘.$gdxApiKey,
‘Content-Type​: ​application/json’,
else//Method GET
‘x-api-key: ‘.$gdxApiKey,
‘Authorization: Bearer ‘.$gdxApiKey,
curl_setopt_array($ch, $curlOptions);
$response = curl_exec($ch);
$arrayInfo[‘header_info’]=curl_getinfo($ch, CURLINFO_HEADER_OUT);
But the header info always gets set as:
‘header_info’ => string ‘POST /v1/reservations?trip >


Content-Type: application/x-www-form-urlencoded
If I remove the CURLOPT_POSTFIELDS option, the headers only gets one “Content-Type” line (application/json, the one that I need)
Any clues?

it doesn´t work … boolean false is returned, while it works using Postman client

How to make a get request to the api using cURL

curl_setopt($ch, CURLOPT_HTTPHEADER, array(
‘Content-Type: application/json’,
‘Content-Length: ‘ . strlen($payload))

You are asking for strlen($payload); which is the string-length while $payload is an array, so that gives an error?

json_encode turns the array into a JSON string, so strlen() will work.

Отправляем данные в формате Json на указанный шлюз методом POST:

Переменная $result будет содержать ответ сервера на переданные данные.

We can’t send post fields, because we want to send JSON, not pretend to be a form (the merits of an API which accepts POST requests with data in form-format is an interesting debate). Instead, we create the correct JSON data, set that as the body of the POST request, and also set the headers correctly so that the server that receives this request will understand what we sent:

All these settings are pretty well explained on the curl_setopt() page, but basically the idea is to set the request to be a POST request, set the json-encoded data to be the body, and then set the correct headers to describe that post body. The CURLOPT_RETURNTRANSFER is purely so that the response from the remote server gets placed in $result rather than echoed. If you’re sending JSON data with PHP, I hope this might help!

101 thoughts on “ POSTing JSON Data With PHP cURL ”

I just had the same challenge the other day and got to the same conclusion as your snippet.

Was fairly well documented on the PHP manual as you also pointed out.

Thanks for sharing this little gem of knowledge.

Thanks, I tried doing something similar style, but didn’t set the header to application/json . I don’t remember if it worked or not (it was a quick four liner suggestion to a colleague). But what happens if you forget setting the application/json header ?

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If you don’t set the header correctly, the service you are posting to may not understand what it is that you sent — the exact outcome depends entirely on the service though

Thanks Lorna.
Looking at replies below (and I don’t know much about script hijacking), I think I will stick setting application/json in the http-header. And if I am writing a server I will (try) not accept simple plain/text.
Ohh BTW, I learned a lot from the slides that you linked in this post. I asked my colleague to read slide 39 — 42 for a quick introduction to SOAP. Pretty interesting stuff !

One thing to note is that some servers will recognize: application/javascript as application/json as well.

many frameworks expect the application/json content type to battle JSON Hijacking.

Well JSON hijacking would be relevant when sending JSON back in the response body, it has no relevance in the request body.

of course — but a server backend could demand that the request contains the Content-type header. JSON Hijacking uses a script tag, which in turn does not allow to set HTTP headers, unlike XmlHttpRequest.

Same thing without curl as a dependency (for the newbies who don’t know about the excellent PHP’s streams API):

$data = array(‘name’ => ‘Hagrid’, ‘age’ => ’36’);
$data_string = json_encode($data);

$result = file_get_contents(‘http://api.local/rest/users’, null, stream_context_create(array(
‘http’ => array(
‘method’ => ‘POST’,
‘header’ => ‘Content-Type: application/json’ . "
. ‘Content-Length: ‘ . strlen($data_string) . "
‘content’ => $data_string,

Thanks for adding the streams example, that’s nice! Streams are pretty awesome but as you say, they’re not as widely used or understood as they should be

hey lorna do you have any idea i got this error? when use the PHP stream
file_get_contents( failed to open stream: HTTP request failed! HTTP/1.1 500 Internal Server Error

@zaadjis i tried your code, it works but i had a warning, it does post those json data but it doesn’t have a response, the warning is this
file_get_contents( failed to open stream: HTTP request failed! HTTP/1.1 500 Internal Server Error

zaadji your are life saver man. I was trying for this. You made simple. Thanks to you and lornajane.

valuable answers for me , thanks alot

+1 zaadjis, I was just thinking about the same.

Actually, you can trim down the request a bit and keep it simple.

You don’t have to specify the content-length. It will be calculated automatically and appended to the headers.

Also, you don’t have to declare the request as a post request explicitly. If you are setting the POSTFIELDS option for curl, curl will convert the request type to POST.

Could you give any examples of any of the discussions you elude to on the topic of accepting POST requests with data in form-format?

Matt, I will put it on my list of "things to blog about some rainy day" 🙂

Thank you very much for this post, I’ve been struggling as a non-programmer to attempt to submit some basic form data to an API and this helped immensely.

For those who are having trouble accessing the data that gets posted use the following:

Thanks Matt. Will try that. And thanks Lorna for the tutorial.

thanks to this I could send JSON to my REST services

This curl example was exactly what I needed tonight. Thanks for sharing.

hi, i’m a total newbie of posting json, REST services and so on but i need to work out this:
in order to get a file from a website that needs a login to get it, from within my app i have to post to a REST service this:

[code] <
"Username":"String content",
"Password":"String content"
to this url: [code]http://www.***.it/***service/***service/novels/[/code] where ID is the file id number and etc
trying with http://username: [email protected] . works for other services but with this service it get "method not allowed"
the webmaster of the site didn’t answer me about it and i’m really tired cause i’m stuck with the work at this point. anyone can help me, please? thanks

matteo: it sounds like the service isn’t expecting you to POST to that URL, but you’d need to talk to the people who created the service to get more information. Sorry I can’t be more help

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PHP4 , curl_setopt($ch, CURLOPT_HTTPHEADER, array(‘Content-Type: application/json’)); is not working. I can’t send the JSON variables in the post method using CURL. IS there any other way to do it?

I’m afraid I’ve never used PHP 4 for this type of thing! I don’t know what kind support there is for curl, or what kind of "not working" your example is. I think there was some stream support in PHP 4, so you could research how to create the context you need to POST your content.

You probably don’t need me to tell you that PHP 4 is no longer supported; I must strongly recommend that you upgrade.

As you explained "how to post JSON data with php CURL". Can you tell me "how to post XML data with php curl."

thanks in advance.

Thanks, this was really helpful. 🙂

I tried catching the results on another PHP file, but it returns no results($_POST is empty). Any idea how this should be done?

You need to put the URL of the file, as if you were web requesting it, in the curl_init call — and then it will receive the POST vars. Whatever your target file outputs you will get back as the response, so you can debug that way, or use a proxy such as Wireshark or Charles to see what is being sent, or not. Hope that helps!

you can post json as it by also .

$(ajax) <

Hei, thanks, it was a fast and simple way to resolve an action of an api I’m working on.

Thanks for posting this. I’d tried a couple of other resources and tried setting curl to send the header that were in-place in the php document however it wasn’t working. When I set it up as in your example it started working. 😀

I call a webservice from a JQuery $.getJSON function, it works fine.
var p = <
‘field1’: ‘value1’,
‘field2’: ‘value2’,
‘field3’: ‘value3’
$.getJSON(‘https://service:[email protected]/service/search?callback=?’, p, function(data) <
if (data[0]) <
// print results
> else <
// no results found

I am trying to connect from PHP and CURL, however it does not work, it always return false.
$params = array( ‘field1’ => ‘value1’, ‘field2’ => ‘value2’, ‘field3’=> ‘value3’);
$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_URL, ‘https://service:[email protected]/service/search?callback=?’);
curl_setopt($ch, CURLOPT_POSTFIELDS, $params);
$result = curl_exec($ch); // return false instead my JSON
$data_string = json_encode($params);
$ch = curl_init(‘https://https://service:[email protected]/service/search?callback=?’);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
‘Content-Type: application/json’,
‘Content-Length: ‘ . strlen($data_string))

$result2 = curl_exec($ch); // // return false instead my JSON

What I am doing wrong?

There are a couple of things to check. I don’t write much JS but your jquery example looks like it’s making a GET request rather than a POST request, so try putting your variables on the end of the URL and using GET from PHP?

Also try checking if you get anything from curl_error($ch) as if the server has any more information, you will find it here.

Hope that helps, and good luck!

only zaadjis methods works for me. thanks a lot zaadjis !

Hey Lorna, thanks for this. Was having an issue with a request to the Open Mapquest API & I think it’s because I wasn’t sending the Content-Length header.

hi Lorna
Thanks. but what about image posting as json using Curl

Hi Lorna
Based on your code i did the following but it is not working what could be the problem ?

"Hagrid", "age" => "36");
//$data_string = json_encode($data);
$str_obj_json=’ <
"method":"SUBMIT","params": <
"userData":"Movistar les desea Feliz Navidad",
$ch = curl_init(‘’);
//curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $str_obj_json);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
‘Content-Type: application/x-www-form-urlencoded’,
‘Content-Length: 395’,
‘Authorization: Basic dGVzdDp0ZXN0’,
‘User-Agent: Wget/1.12 (solaris2.10)’,
‘Connection: Keep-Alive’,
‘Accept: */*’)
$result = curl_exec($ch);

Hard to guess from this example but you are sending JSON as the body while setting the Content-Type header to indication a form submission, set that to "application/json" instead and see if that helps?

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Very nice, that’s just what I was after, no need for all those over the top Libraries for json rpc 2.0

I hacked it a bit so you can work with posted data like so:

$json_req[‘params’] = $myParams;
$json_req[‘jsonrpc’] = ‘2.0’;
$json_req[‘method’] = ‘myMethod’;
$json_req[‘ > curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($json_req));

I am trying to scrap that json data using the script :

$data = array(‘id’ => ‘NBI’, ‘timeOfDay’ => ‘SOD’, ‘tradeDate’=> date(‘Y-m-dTh:i:s.000’));
$data_string = json_encode($data);

$ch = curl_init(‘’);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER , false);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
‘Content-Type: application/json’,
‘Content-Length: ‘ . strlen($data_string))

$result = curl_exec($ch);
else <
echo "";
I am getting the page content but not the json output. Please let me know, where I am wrong.

I am getting the page content but not the json output. Please let me know, where I am wrong.

"CURLOPT_RETURNTRANSFER", this was the exact thing I was looking for to post data to another domain without begin echoed.. came to know by your example. You really saved my day and made my day too.. thanks a lot.

Thanks so much for this post. I was stumped for hours until I found it!

While working with your example, I found that it failed until I changed the JSON conversion line to:
$data_string = "json=" . json_encode($data) . "&";

$data_string = "json=" . json_encode($data) . "&";
$ch = curl_init("http://localhose/parrot.php");
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
$results = curl_exec($ch);

Thanks ! It helped me a lot.
I didn’t write the line with HTTPHEADER and it didn’t work. Now it’s fine 🙂

Great tutorial! Very simple and easy to understand.

Just created a script to get people signup to constant contact mail list from website. This snippet came in handy. Thanks.

Thank you! Web site is great and this code snippet is very clean and usable.

Remember to use mb_strlen($string, ‘8-bit’);

Actually — think the correct is: mb_strlen($string, ‘UTF-8’);

‘8-bit’ is correct as content-length is the number of octets ( which is specified as 8-bits and separate from bytes to remove any confusion. So your emojis aren’t just 1 in terms of content-length 🙂

Thanks Lorna, this was super helpful =)

thanks for this.

trying to get "post json data via api" to work — going nowhere! basic questions:
>the URL i am sending the json data to — what should that page do when it is called?
>what should be on that page? how do i get data there, then calculate using my class, then return the data?
>i feel lost regarding API’s. people post things that seem in the middle of the process. please explain it from the ground up. for hours i view posts that do not really cut to the essence of everything that is going on.
>i already have an index.html that sets up an array, then instantiates my Calculate class that has methods for Mean, Median, Mode, and Range — that works fine. BUT,
>how do i "make it available via an API", and provide the input as JSON, and then output a JSON format?

A more complete explanation is here: "Your client has asked you to make this library available via an API. Your API should implement a single endpoint called "/mmmr" with no query
string parameters. When a POST request is called to "/mmmr", a single JSON object will be passed with an attribute called "numbers". "numbers" is a JSON array of n numbers that should be processed. The script should process the mean, median, mode and range of the numbers and return back a JSON object."

Sample JSON POST body to [single endpoint] /mmmr
"numbers": [
5, 6, 8, 7, 5
Sample JSON Return Response from /mmmr
"results": <
"mean": 6.2,
"median": 6,
"mode": 5,
"range": 3

Your page should do:

Inspect that and you should be able to see the data that you sent to the script. HTH!

Hi Lorna,
Here is my code what I did, but it is not working, can you give some explanation?

curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
‘Content-Type: application/json’,
‘Content-Length: ‘ . strlen($data_string))
curl_setopt($ch, CURLOPT_TIMEOUT, 5);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 5);

//execute post
$response = curl_exec($ch);

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