Languages
Ten, and none of them an afterthought.
Adding a language to a language app is easy. Handling its writing system, its gender system and its sound inventory properly is the part that gets skipped.
What "handled properly" means
The things a bolted-on language gets wrong
Scripts
Japanese and Mandarin carry a reading line above the word. Japanese, Korean, Mandarin, Russian and Arabic carry a transliteration. Arabic runs right to left everywhere, including inside the story reader.
Sound, not spelling
The hook engine folds each language through its own rules before it looks for a keyword, because French spelling and French sound are different problems.
Gender where it exists
Spanish, French, German, Italian, Portuguese, Russian and Arabic carry it in the picture. German gets all three, and the neuter cue is used as often as the other two.
Start with ten words tonight
Thirty days free, no card. When the trial ends the account drops to the free limits and nothing is deleted.