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Smouldering Durtles vs Kakugo: catalog facts
Smouldering Durtles	Kakugo
Free Free and open source under the Apache 2.0 licence; WaniKani itself is a separate service.	Free Free and open source under GPL-3.0.
Android	Android
Native Android interface for WaniKani lessons and reviews Continues a well-known open-source client that was no longer maintained	Covers hiragana, katakana and kanji Adapts review to the learner's pace
Only useful with a WaniKani account Android only	Focused on memorisation, not grammar or speaking Android only
Downloadable app	Downloadable app
Open source	Open source
License: Apache-2.0	License: GPL-3.0
Account needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.