The German language can count on the Goethe-Institut as a German public institution that promotes, spreads and divulges the knowledge of this language. In addition, it seeks to promote Foreign Relations between Germany and other countries. On their website, you can find a long list of dictionaries, both monolingual and bilingual, from and to German.
Follow the link below to see the list:
https://www.goethe.de/prj/mwd/es/ber/lti.html
We also have the Die maßgebende Instanz für die deutsche Rechtschreibung or German Orthography Council, which is the main international organisation that regulates the orthography of the language. On their website, you can find documents that show the constant evolution of the German language in all areas and the preservation of its orthography as a whole.
https://www.rechtschreibrat.com/
Moreover, you can find the Regeln und Wörterverzeichnis section, an orthography database with basic concepts and German spelling that sets the official standard and the primary method of the language. The dictionary contains 12000 entries, some of them with spelling variants.
https://www.rechtschreibrat.com/regeln-und-woerterverzeichnis/
Another useful resource is the German dictionary Duden, first published in 1880 and followed by 25 editions. It is regularly updated with a new edition every 4 or 5 years. This dictionary is considered one of the most used resources globally, by both native Germans and professional translators.
Follow the link below for the online version of the dictionary: