• Your web server must support URL rewriting
• PHP 7.2 or newer

You’ll need the Composer tool. You can download it from the Composer website, or install it from your package manager.

Go to the root folder of your project, and execute this command to install the Slim dependencies:

composer require slim/slim:"4.*"

The Slim files will be placed in your project’s vendor/ directory.

You’ll also need to install a PSR-7 implementation. Slim supports several. I used Slim PSR-7:

composer require slim/psr7

The PSR-7 files will also be placed in the vendor/ directory.

Create a public/ folder to hold your project files. You’ll now have two sub-directories in your project root, vendor/ and public/.

Create an .htaccess file in public/, and add the following contents:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^ index.php [QSA,L]

Create an index.php file in public/, and add the following contents:

index.php

<?php
 
use Psr\Http\Message\ResponseInterface as Response;
use Psr\Http\Message\ServerRequestInterface as Request;
use Slim\Factory\AppFactory;
 
require __DIR__ . '/../vendor/autoload.php';
 
$app = AppFactory::create();
 
$app->get('/', function ($request, $response, $args) {
$response->getBody()->write("Hello world!");
return $response;
});
 
$app->get('/value/{id}', function ($request, $response, $args) {
$passed_value = $args['id'];
$response->getBody()->write("Value is $passed_value");
return $response;
});
 
$app->run();

To test your new project, cd into public/, and start a PHP development server instance:

php -S localhost:8080

Open a web browser, and navigate to http://localhost:8080. You should see the following:

Hello world!

Navigate to http://localhost:8080/value/2. You should see the following:

Value is 2

You now have a simple starting configuration, with routing for the root URL, and also a simple RESTful endpoint at /value/{id}.

The entire project folder must be deployed to your web server, but the project should be served from the public/ directory.

For example, let’s say that you want your new service to be published in a subdomain at https://myservice.<your_domain_name>.com/:

1. Create a directory for your project on your web server, e.g., /home/<username>/www/myservice.
2. Upload your entire project folder to /home/<username>/www/myservice.
3. Configure the new subdomain https://myservice.<your_domain_name>.com/ to be served from /home/<username>/www/myservice/public.