Add Beehiiv Subscriber via API

subscribe-beehiiv-api.php

<?php
/**
 * This file subscribes a subscriber to Beehiiv via API. 
 * Documentation: https://developers.beehiiv.com/api-reference/subscriptions/create
 */

/**
 * Change this to your publication ID.
 *
 * @return string
 */
function get_beehiiv_publication_id() {
    return 'pub_***';
}

/**
 * Change this to your API key.
 *
 * @return string
 */
function get_beehiiv_api() {
    return '***';
}

/**
 * Subscribe to Beehiiv via API.
 *
 * @param $data
 * @return false|mixed
 */
function subscribe_beehiiv( $data ) {
    $publication_id = get_beehiiv_publication_id();
    $api_key        = get_beehiiv_api();
    $curl           = curl_init();

    curl_setopt_array($curl, [
        CURLOPT_URL => "https://api.beehiiv.com/v2/publications/$publication_id/subscriptions",
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_ENCODING => "",
        CURLOPT_MAXREDIRS => 10,
        CURLOPT_TIMEOUT => 30,
        CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
        CURLOPT_CUSTOMREQUEST => "POST",
        CURLOPT_POSTFIELDS => json_encode( $data ),
        CURLOPT_HTTPHEADER => [
            "Accept: application/json",
            "Authorization: Bearer $api_key",
            "Content-Type: application/json"
        ],
    ]);

    $response = curl_exec($curl);
    $err      = curl_error($curl);

    if ( $err ) {
        return false;
    }

    curl_close($curl);

    $response = json_decode( $response, true );

    return $response['data']['id'];
}

/**
 * Subscriber data.
 */
$email          = '[email protected]';
$utm_campaign   = 'Test Campaign';
$utm_source     = 'Test Source';
$utm_medium     = 'Test Medium';
$referring_site = 'test.com';
$first_name     = 'Test';
$last_name      = 'Test';

$custom_fields  = [];

if ( $first_name ) {
    $custom_fields[] = [
        'name'  => 'First Name',
        'value' => $first_name,
    ];
}

if ( $last_name ) {
    $custom_fields[] = [
        'name'  => 'Last Name',
        'value' => $last_name,
    ];
}

$subscription_id = subscribe_beehiiv(
    [
        'email'          => $email,
        'utm_source'     => $utm_source,
        'utm_campaign'   => $utm_campaign,
        'referring_site' => $referring_site,
        'custom_fields'  => $custom_fields,
    ]
);