The code is very well organized, I’m on my phone and could easily navigate it.

But some stuff twists my nose: 1. No dependencies is cool up to some point, I personally do not try that so I avoid reinventing the wheel. You are prone to have many bugs the community already solved, the trade off end up not being worth the hassle.

2. I see you have many classes but many ones with only static methods. That’s basically global functions that can’t be easily mocked for unit tests and create highly coupled code.

3. Lack tests. Even though you may know the functionality/code from top to bottom, no tests make you prone to break unrelated stuff when writing new code.

Again, nice to see it, awesome you shared! If you want to step up the game https://phptherightway.com/ has a lot of material and references for that.