What file system for sdcard for KitKat I have been searching the web and this website for information about the file systems supported by Android. I have not found anything though.

Since KitKat (Android 4.4), some changes have been applied regarding the access of the applications to the external SD cards. Many websites explain, pretty well, that this is due to Android offering read/write access control over the folders and FAT file system not offering this feature.

This is nice to know the cause but now I am interested in finding a solution. Not a workaround that involves an app or whatever, but I would like to know which file system I can format my sd card with and Android recognizes it. I vaguely read about EXT, but which version? Does Android work with EXT 3, 4?

By the way, I apologize if this has been asked, let me know the duplicate in that case.
This limitation is not due to the FAT filesystem : Since 4.4, Android only lets a special user group write on the card.

Your card could be in NTFS, or EXT or whatever more, you'll have the same problem.

The only way to bypass this limitation is to root your device, and install some 3rd party apps/patchs, or manuallay edit some files.