Apps like Challenge with Erin! Japanese

Here are some great alternatives to Challenge with Erin! Japanese by The Japan Foundation :
Tobo Learn Japanese Vocabulary
Tobo Learn Japanese Vocabulary
★4.6
Japanese Study (hiragana)
Japanese Study (hiragana)
★4.6
Memorize: Learn Japanese Words
Memorize: Learn Japanese Words
★4.4
Japanese characters
Japanese characters
★4.4
JLPT Learn Japanese Vocabulary
JLPT Learn Japanese Vocabulary
★4.3
Japanese Remember, JLPT N5~N1
Japanese Remember, JLPT N5~N1
★3.6
JLPT N4&N5 Vocabulary - Minano
JLPT N4&N5 Vocabulary - Minano
★4.6
Learn Japanese-Hiragana-Romaji
Learn Japanese-Hiragana-Romaji
★3.4
Kana Quiz Japanese
Kana Quiz Japanese
★4.5
Obenkyo
Obenkyo
★4.6
Japanese Kanji Study
Japanese Kanji Study
★4.5
renshuu - Japanese learning
renshuu - Japanese learning
★4.8
Japanese Study Kanji JLPT
Japanese Study Kanji JLPT
★4.2
Japanese characters (PLUS)
Japanese characters (PLUS)
★4.7
JLPT Test N5 N4 N3 N2 N1
JLPT Test N5 N4 N3 N2 N1
★4.2
Asahi Kanji (English)
Asahi Kanji (English)
★4.8