Hi there,

I'm interested in to start to develop for KDE plasma 5 and I like to use an IDE software.

My question is which IDE software should I use and which frameworks are needed. I use Debian 9 at the moment. The Internet will not show me what I'm looking for.

I found the "Qt developer" but maybe it's not enough to start because it will show in the wizard KDE 4 only.

Thank you in advance for tips. (I develop with Android Studio at the moment and PhpStorm)

I think the top choices that I've seen are:
* KDevelop is built using KDE technologies and is your more traditional c/c++/python focused IDE.
* PlasMate is a purpose-built IDE/studio designed primarily for developing Plasma Widgets.
* Qt Creator is built using (pure) Qt, and is also a more traditional qt-focused IDE.

These should all be available in your distro's repos (or through appropriate channels if you are on Windows).
Of course if you are familiar with other IDEs which work with c/c++/qt projects, you should be able to use those with KDE projects as well. I believe Android Studio is built on Eclipse, so you may be able to use Eclipse. Having used PhpStorm, you could try out CLion. (looks like CLion fully integrates with CMake, which KDE projects generally use; while Eclipse does not, integrating instead with the makefile that cmake generates)

As for getting started, I'd suggest you start by poking around the community wiki page for Getting Involved which should have links to build instructions and things.
Kdevelop has a convenient feature that when fetching/opening a project you can select that you want to fetch a KDE project and it should list out the available KDE projects for you to check out (and similarly for github projects, after you've selected a github user/organization).