Insert a post into WordPress from an external script

insert-posts.php

<?php

// Load WordPress
require_once 'path/to/www/wp-load.php';
require_once ABSPATH . '/wp-admin/includes/taxonomy.php';

// Set the timezone so times are calculated correctly
date_default_timezone_set('Europe/London');

// Create post
$id = wp_insert_post(array(
    'post_title'    => $title,
    'post_content'  => $content,
    'post_date'     => date('Y-m-d H:i:s'),
    'post_author'   => $user_id,
    'post_type'     => 'post',
    'post_status'   => 'publish',
));

if ($id) {

    // Set category - create if it doesn't exist yet
    wp_set_post_terms($id, wp_create_category('My Category'), 'category');

    // Add meta data, if required
    add_post_meta($id, 'meta_key', $metadata);

} else {
    echo "WARNING: Failed to insert post into WordPress\n";
}