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Smouldering Durtles vs Renshuu: catalog facts
Smouldering Durtles	Renshuu
Free Free and open source under the Apache 2.0 licence; WaniKani itself is a separate service.	Freemium Free to start learning, with optional paid features.
Android	Android, iOS, Web
Native Android interface for WaniKani lessons and reviews Continues a well-known open-source client that was no longer maintained	Vocabulary, kanji and grammar in one place Dictionaries filterable by JLPT level
Only useful with a WaniKani account Android only	Japanese only Requires an account to track progress
Downloadable app	Downloadable app, Web application
Open source	Closed source
License: Apache-2.0	License not stated
Account needed	Account 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 September 24, 2026

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