There are many certificates and exams to show your CEFR level of German. So many, so many times you can’t understand the differences between them. And, even though I still have some dilemmas, I will briefly present the certificates by which you can prove that you know German:
Goethe-Zertifikat. By far the best known certificate, mainly because there are many exam centers around the world (as opposed to other types of diplomas, such as DTZ or ÖSD). It has several types of exams: 6 exams for adults (from CEFR A1 to CEFR C2), 6 exams for children (from A1 to C2) and professional certificates for the medical field and for other various fields. There are four parts (Writing, Reading, Listening, Speaking) and the maximum score is 100 (the minimum being 0). The cost of the exam differs depending on the level: The A1 level is about 70€ and the C1 one costs 300€.
TestDaF. TestDaF is the abbreviation for Test Deutsch als Fremdsprache. Although, theoretically, TestDaF is a certificate for anyone, regardless of age or education, almost everyone who takes the TestDaF exam does so because they want to apply to a university in Germany. Grades are given for each section (Writing, Reading, Listening, Speaking) and are from 1 to 5. As a rule, universities require an average grade of at least 4. High school students prefer to give TestDaF and because universities require Goethe C2 for admission, whereas to take TestDaF with a minimum grade of 4 you must be B2 or C1. Unfortunately, there are not many exam centers, I think there are only 50 in Europe.
ÖSD. Österreichisches Sprachdiplom Deutsch (or ÖSD) is the certificate for attesting knowledge of the German language issued by the Austrian Ministry of Education. If you want to apply for Austrian citizenship or want a job in Austria, the ÖSD is the right certificate for you. From what I noticed, ÖSD places more emphasis on Reading (Lesen) than other exams like Goethe Zertifikat.
DSH. Deutsche Sprachprüfung für den Hochschulzugang (or DSH) is another certificate of proficiency to be able to apply for a German university. I don’t understand the difference between DSH and TestDaF, apart from the fact that there are not many examination centers for DSH. There are 4 parts of this exam (Lesen, Schreiben, Sprechen, Hören), and the DSH grading scale is between 1 and 3, where 3 is the maximum score and 1 is the minimum score.
Proficiency levels according to the Common European Framework of Reference (CEFR):
DSH 1 (≥57%): Level B2
DSH 2 (≥67%): Level C1
DSH 3 (≥82%): Level C2 (from Wikipedia)
telc. The European Language Certificates (or telc) is a private company that offers proficiency certificates for several foreign languages, including German. Although the German state does not recognize telc exams, German universities and companies will most likely recognize such a certificate.
DTZ. Deutsch-Test für Zuwanderer (DTZ) is an exam organized by the TELC company and is only for A2 and B1 levels. It costs about 100€.
Deutsches Sprachdiplom. Deutsches Sprachdiplom der Kultusministerkonferenz is an exam organized by the Auswärtiges Amt (German Foreign Office) and is aimed especially at high school and middle school students. The DSD was made especially to promote German language learning worldwide. DSD 1 is aligned to the A2/B1 level, while DSD 2 is aligned to the B2/C1 level.
KDS. Kleines Deutsches Sprachdiplom (or KDS) is a certificate oriented to German literature, aligned with the C2 level.