Sirius Pro

Simply Remove Category Base URL and show only category name in WordPress permalink. This plugin allows you to easily disable category base from URL without modifying the code and it works with most of the available themes. Just install and activate this plugin to remove category base from URL in WordPress.
Read more about this plugin on <a href="https://siriuspro.pl" rel="nofollow ugc">WordPress</a> blog.

Category Base

Simply Remove Category Base from URL and show only category name in WordPress permalink.

texttheater

NOTE: recent WordPress versions already properly transliterate umlauts if the 
site language is German. In that case, German Slugs is no longer needed.
While creating a post or page, WordPress automatically suggests a permalink. If 
your permalink structure contains the %postname% tag, then the title of your 
post or page will be used, simplified by conversion to lowercase, replacing 
spaces with hyphens, removing certain punctuation characters and removing 
diacritics from latin letters.
Thus, by default, ä is replaced with a, ö with o, ü with u and ß with s (similar 
for capital letters). For German, the conventional transliteration is ä to ae, ö 
to oe, ü to ue and ß to ss (sometimes sz in Austria, this is not yet supported). 
This plugin makes your WordPress apply the conventional transliteration.
I wrote this plugin because manually correcting WordPress’s suggestions is a 
considerable hassle, especially if you decide to change the title afterwards.
<h3>Support</h3>
If you have questions or suggestions, contact me at poststelle ät texttheater döt 
net.

German Slugs

German Slugs properly transliterates umlauts and the letter ß appearing in titles for slugs (i.e. for pretty permalinks).

Category Base vs German Slugs