Can I use EditorGUI class outside Unity?

I’m trying to create and aplication, and things like the color picker or Vector fields could be very useful, but they all seem bugged if I use it on the project itself, is there anyway to use theese tools?, or I have to make them from scratch

Google around for what you need. Short answer: if it’s and Editor script, you can’t use it in your runtime, but people have made many classes that do similar things, color pickers are among them.