[djmakinera]

How to change the file extension? Although at the end I added the zip extension it is still oxt

[Jiaz]

What exactly do you mean? Just rename the file manually or via packagizer!?

[djmakinera]

I mean change of extension, not name!
I downloaded the *.oxt files, but I want to change the extension to *.zip to unpack all files.

filename.zip.oxt - still not a valid .zip extension

[Jiaz]

I'm sorry but I don't understand? how about just remove the .oxt ?!
You can either rename them one by one or with mass rename and regular expression

[djmakinera]

I've already downloaded all the files. I can not delete an extension in the Windows System, sometimes it is impossible with some files. Need to change this in another advanced program to change the file extension. For example, in the "Advanced Renamer" tool or in the Total Commander.

[Jiaz]

You can always change extension but you have to disable *hide file extension* in file explorer. Or you use mass renaming tools
In case the files are still in JDownloader list, you can rename them there as well