Do you want to share posts on LinkedIn using PHP? You may wish to build an automated system that can share your post on LinkedIn programmatically. 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 that will give you genuine readers.

If you have a lot of posts being written 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 a title, description, and image on your feed.

We will go through all the steps required for sharing a post on LinkedIn. These steps include

• Register an application on LinkedIn Developer Network.
• Generate an access token. We’ll build OAuth flow to grab the access token.
• Fetch your LinkedIn profile ID.
• Finally, send a post on your LinkedIn Feed.

Create LinkedIn Application

In order to start with Share API, you first need to register the application with your LinkedIn Developer account. Integrating LinkedIn APIs requires having the access token. And this access token is created using your application’s keys – client id and client secret.

While registering the application, you also need to set an authorized redirect URL. 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 prompted.
• Add http://localhost/linkedin/callback.php in the Authorized Redirect URLs field.
• Under the ‘Products’ tab, select 2 products – Sign In with LinkedIn and Share on LinkedIn.
• Copy the Client ID and Client Secret keys.

Generate an Access Token for 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. LinkedIn verifies this access token and then performs the requested operations.

To generate an access token, you need to authorize your account. This authorization can be done via OAuth. During this process, you need to send HTTP requests to the OAuth endpoint. To send the HTTP requests and handle the response, install the Guzzle library using the Composer command.

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 enough for our end goal.

Build an Authorization URL

It needs to build an authorization URL to fetch the access token. This URL requires a client_id, redirect_uri, and scope as additional parameters. The 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. In this callback URL, we’ll write a code to grab the access token.

Let’s create a index.php and add the code to generate the 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 I said after completing the authorization, you will redirect back to the callback URL. When it comes back, it has the Authorization code in the get parameter. From the callback file, we’ll send a POST request to the LinkedIn API along with the required parameters including this authorization code. In return, LinkedIn API provides 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. The access token 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

You got the access token for your LinkedIn account. The next part is fetching your LinkedIn ID. This ID is required to share a post on your LinkedIn feed. 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 also store this LinkedIn ID. You will require both the access token and LinkedIn ID in the next step.

Send Post on LinkedIn Using LinkedIn API and PHP

Now the last step is to send a post on LinkedIn. The Share API documentation explains the request format required to execute this operation. 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 'Post is shared on LinkedIn successfully.';
    } else {
        echo 'Error: '. $response->getLastBody()->errors[0]->message;
    }
} catch(Exception $e) {
    echo $e->getMessage(). ' for link '. $link;
}

In the above code, I have added a few placeholders that should be replaced with their 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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