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Mailvelope vs OpenKeychain: catalog facts
Mailvelope	OpenKeychain
Free Free and open source for personal use. Business products are paid.	Free Free and open source, supported by donations.
Browser extension	Android
Works inside existing webmail rather than requiring a desktop mail client Keys stay in the browser under your control	Compatible with OpenPGP software on other platforms Provides encryption to other Android apps such as K-9 Mail
Only supports a defined list of webmail sites Browser-based key storage is weaker than a dedicated client or smartcard	Android only Using OpenPGP keys well requires some understanding of how key exchange works
Browser extension	Downloadable app
Open source	Open source
License: AGPL-3.0	License: GPL-3.0
Not stated if an account is needed	No account needed
Not stated if it works offline	Works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked September 23, 2026

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