No Fluff: Katakana is probably one of the simplest tools to improve the recognition of katakana.
As soon as you launch the app, the quizzing starts. In total there are 104 items: ア, イ, ウ, エ, オ, カ, キ, ク, ケ, コ, サ, シ, ス, セ, ソ, タ, チ, ツ, テ, ト, ナ, ニ, ヌ, ネ, ノ, ハ, ヒ, フ, ヘ, ホ, マ, ミ, ム, メ, モ, ヤ, ユ, ヨ, ラ, リ, ル, レ, ロ, ワ, ヲ, ン, ガ, ギ, グ, ゲ, ゴ, ザ, ジ, ズ, ゼ, ゾ, ダ, ヂ, ヅ, デ, ド, バ, ビ, ブ, ベ, ボ, パ, ピ, プ, ぺ, ポ, キャ, キュ, キョ, シャ, シュ, ショ, チャ, チュ, チョ, ニャ, ニュ, ニョ, ヒャ, ヒュ, ヒョ, ミャ, ミュ, ミョ, リャ, リュ, リョ, ギャ, ギュ, ギョ, ジャ, ジュ, ジョ, ビャ, ビュ, ビョ, ピャ, ピュ and ピョ. Your task is to recognize the corresponding romaji of all of these shuffled items among four choices per item.
There are no ads, no internet access is required once the app is downloaded, no data is collected, it's as simple as that. Furthermore, you can inspect and improve the source code through the website.
This is not a tool to learn katakana (even though it could be used for that), but to improve recognition (speed) of katakana.
Published as Android app in Google Play Store.