German, graded from A1 to C2.

15,003 words from A1 to C2, commonest first: nouns with their article, plural and genitive, verbs with their principal parts and auxiliary, each with real example sentences and native audio where a recording exists. 276 graded reading texts with an English translation for every line. 13,725 conjugation and declension tables, with the mistakes real learners make in exam scripts. 5,379 practice questions in five exam formats (gap-fill, articles, grammar, comprehension, true/false), every answer explained.

The word lists, flashcards and grammar tables are free, with no account. So are the first reading text and the first immersion video at each level, and Test 1 of each grammar and vocabulary set. The other reading texts and videos, the other tests, the listening tests, writing tasks, speaking exams and the AI tutor are for members. The underlying data is published under CC BY-SA 4.0.

Six, from A1 to C2. A1 and A2 are the basic user, B1 and B2 the independent user, C1 and C2 the proficient user. German exams map onto them directly: Goethe-Zertifikat A1 through C2, telc Deutsch A1 through C1, and TestDaF around B2–C1.

A quick test: open a level's word list and read down the first stretch of it. If you know almost every word, that level is behind you. If you know about two-thirds, that is where to study. Under half, drop a level. Do the same with a B1 reading text. Comfortable reading is a better signal than a self-assessment questionnaire.

Around 5,144 words gets you to B2, which is the level most people mean by "fluent": you can follow a normal conversation, read a newspaper and work in German. The first 1,000 do most of the work: they cover the majority of what is actually said.

The word list and its grammar come from Wiktionary, with levels up to B1 from the Goethe-Institut word lists; example sentences from Tatoeba and an open subtitle corpus; the reading texts from Klexikon, a German encyclopaedia written for children, with A2 drawn from the Leichte-Sprache wikis MiniKlexikon and Hurraki. The A1 texts were written by AI from the A1 word list, because no wiki is simple enough for a first 600 words. The translations, glossaries, short word meanings, grammar point explanations and most practice questions were written by AI models and checked automatically, not by a teacher. Full details, model by model, on the attribution page.