Forces all WordPress lowercase URLs

force-lowercase-urls.php

<?php
/**
 * Plugin Name: Force Lowercase URLs
 * Description: Forces all lowercase URLs
 * Version:     1.0
 * Author:      Zachary Scott
 */


if( ! is_admin() ){
	add_action( 'init', 'zs_force_lower_urls' );
}

function zs_force_lower_urls(){

	$url = $_SERVER['REQUEST_URI'];

	if ( preg_match( '/[\.]/', $url ) ){
		return;
	}

	if ( preg_match( '/[A-Z]/', $url ) ) {
		$lc_url = strtolower( $url );
		header( "Location: " . $lc_url, true, 301);
		exit( 0 );
	}

}