Slim

Slim is a small PHP framework for building web applications and APIs. PHP is a programming language commonly used to build websites, and a "framework" is a pre-built structure that handles common tasks so you do not have to write everything from scratch. Slim is described as a "micro" framework, meaning it provides only the essentials: routing (deciding what code runs when someone visits a URL), error handling, and a way to send back HTTP responses.

Installing it requires a tool called Composer, which is the standard package manager for PHP projects. Once installed, you define routes in code by specifying a URL pattern and a function that runs when someone visits that URL. The included example shows how a few lines of PHP can respond to a request like "/hello/world" with the text "Hello, world."

Before you can use Slim, you also need to pick a PSR-7 implementation. PSR-7 is a shared standard that defines how HTTP requests and responses should be represented as PHP objects. Slim itself is not tied to one specific implementation, so the README lists several options (including one from Slim's own team, plus others from third parties) and explains how to install each. This flexibility is a deliberate design choice, but it does mean there is one extra decision to make before you can run your first request.

Slim also includes an optional add-on library called Slim-Http, which wraps whichever PSR-7 implementation you chose and adds extra convenience methods. This is described as recommended but not required.

The project has a test suite, a community forum, a Slack channel, and a documentation website. Security issues have a dedicated email address rather than the public issue tracker. The README also mentions an enterprise support option via a third-party subscription service for organizations that need commercial backing.