# Slim — Lightweight PHP Micro Framework for REST APIs

> Slim is a PHP micro framework that helps you write simple yet powerful web applications and APIs with minimal overhead, offering PSR-7 HTTP message support and a fast middleware-based architecture.

## Install

Save in your project root:

# Slim — Lightweight PHP Micro Framework for REST APIs

## Quick Use
```bash
composer require slim/slim slim/psr7
```
```php
use SlimFactoryAppFactory;
$app = AppFactory::create();
$app->get("/hello/{name}", function ($req, $res, $args) {
    $res->getBody()->write("Hello, " . $args["name"]);
    return $res;
});
$app->run();
```

## Introduction
Slim is a PHP micro framework designed for building APIs and small-to-medium web applications. It implements PSR-7 HTTP messages and PSR-15 middleware, giving developers a thin but standards-compliant layer between an HTTP request and response without the overhead of a full-stack framework.

## What Slim Does
- Routes HTTP requests to callable handlers using a fast, tree-based router
- Implements PSR-7 request/response interfaces for interoperable HTTP handling
- Supports a middleware pipeline for cross-cutting concerns like auth and CORS
- Provides dependency injection via any PSR-11 compatible container
- Handles error rendering with customizable error handlers and formatters

## Architecture Overview
Slim's core is a dispatcher that wraps a PSR-7 request through a middleware stack, matches the URI against registered routes, invokes the matched callable, and returns the PSR-7 response. The framework has no ORM, templating engine, or built-in auth — those are added via Composer packages, keeping the core under 70 KB.

## Self-Hosting & Configuration
- Requires PHP 8.1+ and Composer
- Install with `composer require slim/slim` plus a PSR-7 implementation
- Entry point is typically `public/index.php` behind Apache or Nginx
- Configure via PHP arrays or a PSR-11 container; no YAML or INI files needed
- Deploy to any PHP-capable host, Docker, or serverless (AWS Lambda via Bref)

## Key Features
- PSR-7 and PSR-15 compliance ensures interoperability with the PHP ecosystem
- Minimal footprint keeps startup time and memory usage low
- Flexible middleware architecture for layering functionality
- Route groups with shared middleware for clean API versioning
- Built-in support for content negotiation and response formatting

## Comparison with Similar Tools
- **Laravel** — full-stack with ORM, queues, and auth; Slim is minimal and bring-your-own
- **Symfony** — enterprise component library; Slim is a single micro framework
- **Lumen** — Laravel-flavored micro framework; Slim is framework-agnostic and PSR-first
- **CodeIgniter** — lightweight but opinionated MVC; Slim has no view layer
- **Mezzio (Laminas)** — PSR-15 micro framework; Slim offers simpler API with less configuration

## FAQ
**Q: Is Slim suitable for large applications?**
A: Slim can power large apps when combined with a container, ORM, and templating engine, but a full-stack framework may be more productive at scale.

**Q: How do I add templating?**
A: Install a renderer like `slim/twig-view` or `slim/php-view` and register it in the container.

**Q: Does Slim support WebSockets?**
A: Not natively. Slim handles HTTP request-response cycles; use Ratchet or Swoole for WebSockets.

**Q: What changed in Slim 4?**
A: Slim 4 decoupled the PSR-7 implementation, adopted PSR-15 middleware, and requires an explicit PSR-11 container.

## Sources
- https://github.com/slimphp/Slim
- https://www.slimframework.com/docs/v4/

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Source: https://tokrepo.com/en/workflows/asset-b79ff53e
Author: AI Open Source