If you don't want a framework, why do you want a framework? Picking an old, barely-used framework because it pitches itself as "fat-free" is a mistake: either use a good, modern, widely-used framework (like Laravel or Symfony) and benefit from a cohesive framework experience OR skip the framework altogether and grab best-in-class packages for each of the individual things you need and wire them together yourself. You could probably get all of what you need out of PHP League's packages: https://thephpleague.com/