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Memento vs Language Reactor: catalog facts
Memento	Language Reactor
Free Free and open source under the GPL-2.0 licence.	Freemium Free to use, with additional features in a paid tier.
Windows, macOS, Linux	Browser extension
Popup dictionary over subtitles using Yomitan dictionaries One-step Anki card creation via AnkiConnect	Dual subtitles on Netflix and YouTube Uses real native material instead of textbook content
Focused on Japanese only macOS build is for Apple Silicon (arm64)	Depends on third-party streaming sites that can change their players Proprietary
Downloadable app	Browser extension
Open source	Closed source
License: GPL-2.0	License not stated
No account needed	Not stated if an account is needed
Works offline	Needs internet
Official website Full listing and sources Checked October 1, 2026	Official website Full listing and sources Checked September 23, 2026

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