Do you want to know how to share posts on LinkedIn using PHP? In this article, I show you how to send a post on LinkedIn using LinkedIn API and PHP.

Sharing posts on social networks helps you to bring more traffic and audiences to your website. LinkedIn is a professional network so it would have a high chance of getting genuine readers.

If you are running a website then posting a link manually on LinkedIn is not a wise choice. It is always better to have an automated system that sends a post on your feed programmatically.

LinkedIn provides a Share API using which you can post a link along with title, description, and image on your feed.

In this tutorial, we will go through all the steps required for sharing a post on LinkedIn. This will include stuff like creating a LinkedIn application, generate an access token, get a LinkedIn profile id, and finally send a post on LinkedIn.

Create LinkedIn Application

In order to start with LinkedIn share API, you first need to create the application with your LinkedIn account. Integrating LinkedIn APIs requires a client id and client secret. You also need to set an authorized redirect URL in your application.

For testing purposes, I am going to use my local server URL. You should adjust this URL as per your flow.

• Go to LinkedIn Developer Network.
• Click on the ‘Create App’ button.
• Complete the setup as per LinkedIn guidelines.
• Add http://localhost/linkedin/callback.php in the Authorized Redirect URLs field.
• Under the ‘Products’ tab, select the product ‘Sign In with LinkedIn’.
• Copy the Client ID and Client Secret keys.

Generate an Access Token of LinkedIn Account

An access token is an identifier that is required to perform API operations on the user’s account. Sharing posts programmatically on LinkedIn requires an access token.

To generate an access token, you need to authorize your account. During this process, we need to send HTTP requests to the APIs endpoint. We are going to install the Guzzle library which allows us to send HTTP requests and receive the response.

Run the command below in your project root directory to install the Guzzle library.

composer require guzzlehttp/guzzle

Next, create a config.php file and pass the credentials in the file as shown below.

<?php
define('CLIENT_ID', 'YOUR_CLIENT_ID');
define('CLIENT_SECRET', 'YOUR_CLIENT_SECRET');
define('REDIRECT_URL', 'http://localhost/linkedin/callback.php');
define('SCOPES', 'r_emailaddress,r_liteprofile,w_member_social');

Make sure to replace placeholders with actual values. Here, I set my local server URL as a ‘REDIRECT_URL’. In your case, this URL is different. To the ‘SCOPES’ constant, I have passed the default permissions which are sufficient for our end goal.

Build an Authorization URL

In order to get your access token, it needs to build an authorization URL. This URL requires a client_id and redirect_uri as an additional parameter. Authorization URL takes you to the LinkedIn website where you have to complete the authentication. After completing authentication, you will redirect back to the callback URL.

Let’s create a index.php and add the code for authorization URL as follows.

<?php
require_once 'config.php';
 
$url = "https://www.linkedin.com/oauth/v2/authorization?response_type=code&client_id=".CLIENT_ID."&redirect_uri=".REDIRECT_URL."&scope=".SCOPES;
?>
 
<a href="<?php echo $url; ?>">Login with LinkedIn</a>

Exchange Authorization Code for an Access Token

As said after completing the authorization, you will redirect back to the redirect URL along with the Authorization Code. In the callback file, we have to write a code that sends a POST request with required parameters to the LinkedIn API and receives an access token.

callback.php

<?php
require_once 'config.php';
require_once 'vendor/autoload.php';
use GuzzleHttp\Client;
 
try {
    $client = new Client(['base_uri' => 'https://www.linkedin.com']);
    $response = $client->request('POST', '/oauth/v2/accessToken', [
        'form_params' => [
                "grant_type" => "authorization_code",
                "code" => $_GET['code'],
                "redirect_uri" => REDIRECT_URL,
                "client_id" => CLIENT_ID,
                "client_secret" => CLIENT_SECRET,
        ],
    ]);
    $data = json_decode($response->getBody()->getContents(), true);
    $access_token = $data['access_token']; // store this token somewhere
} catch(Exception $e) {
    echo $e->getMessage();
}

Upon receiving the access token, save it in a safe place. You may store it in the database. LinkedIn does not generate long-lived access tokens. It is valid for 60 days. You need to regenerate an access token before expiry by following the above process again. It is a kind of ugly thing but currently, programmatic refresh tokens(which are used to regenerate access tokens in the background) are available for a limited set of partners only. You may read more about this on LinkedIn documentation.

Get Your LinkedIn ID using API

You got the access token of your LinkedIn account. The next part is to get your LinkedIn ID. This ID is required to share a post on LinkedIn. Get this ID by sending a GET request to the LinkedIn API endpoint /v2/me.

<?php
require_once 'config.php';
require_once 'vendor/autoload.php';
use GuzzleHttp\Client;
 
$access_token = 'YOUR_ACCESS_TOKEN';
try {
    $client = new Client(['base_uri' => 'https://api.linkedin.com']);
    $response = $client->request('GET', '/v2/me', [
        'headers' => [
            "Authorization" => "Bearer " . $access_token,
        ],
    ]);
    $data = json_decode($response->getBody()->getContents(), true);
    $linkedin_profile_id = $data['id']; // store this id somewhere
} catch(Exception $e) {
    echo $e->getMessage();
}

Like an access token, you should store this LinkedIn ID. We will require both the access token and LinkedIn ID in the next step.

Send Post on LinkedIn Using LinkedIn API and PHP

Now our last step is to send a post on LinkedIn. The Share API documentation explains the request format needed. Taking a reference from it, our PHP code would be as follows:

<?php
require_once 'vendor/autoload.php';
use GuzzleHttp\Client;
 
$link = 'YOUR_LINK_TO_SHARE';
$access_token = 'YOUR_ACCESS_TOKEN';
$linkedin_id = 'YOUR_LINKEDIN_ID';
$body = new \stdClass();
$body->content = new \stdClass();
$body->content->contentEntities[0] = new \stdClass();
$body->text = new \stdClass();
$body->content->contentEntities[0]->thumbnails[0] = new \stdClass();
$body->content->contentEntities[0]->entityLocation = $link;
$body->content->contentEntities[0]->thumbnails[0]->resolvedUrl = "THUMBNAIL_URL_TO_POST";
$body->content->title = 'YOUR_POST_TITLE';
$body->owner = 'urn:li:person:'.$linkedin_id;
$body->text->text = 'YOUR_POST_SHORT_SUMMARY';
$body_json = json_encode($body, true);
 
try {
    $client = new Client(['base_uri' => 'https://api.linkedin.com']);
    $response = $client->request('POST', '/v2/shares', [
        'headers' => [
            "Authorization" => "Bearer " . $access_token,
            "Content-Type"  => "application/json",
            "x-li-format"   => "json"
        ],
        'body' => $body_json,
    ]);
 
    if ($response->getStatusCode() !== 201) {
        echo 'Error: '. $response->getLastBody()->errors[0]->message;
    }
 
    echo 'Post is shared on LinkedIn successfully.';
} catch(Exception $e) {
    echo $e->getMessage(). ' for link '. $link;
}

In the above code, you have to replace the placeholders with the actual values. After calling the API endpoint /v2/shares, you will get a ‘201’ HTTP code. It means the post is created(shared) on LinkedIn.

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