With support for a host of PSR standards, Slim 4 is the PHP micro framework that enables you to write powerful web applications and APIs that embrace the wider PHP ecosystem and in this talk, I will show how. It takes advantage of many of the FIG group's PSR standards to allow easy interoperability with a large ecosystem of components. We will look at how Slim's middleware system leverages the PSR-15 middleware and request handlers to create easily understandable and flexible applications. We will cover application setup, routing and the relationship between actions and middleware. Dependency injection is very useful in a modern PHP application and we'll look at how to integrate any PSR-11 container with Slim ensuring you can decouple your dependencies. By the end of the session, you will be equipped to use the new Slim 4 to create web applications yourself.