Compare software

MailvelopeFlowCrypt
Free

Free and open source for personal use. Business products are paid.

 Freemium

Free extension for individuals, with paid business plans listed on the pricing page.

Browser extension Browser extension
  • Works inside existing webmail rather than requiring a desktop mail client
  • Keys stay in the browser under your control
  • Works inside the normal Gmail interface
  • Encrypts both messages and attachments
  • Only supports a defined list of webmail sites
  • Browser-based key storage is weaker than a dedicated client or smartcard
  • Built around Gmail rather than other mail providers
  • Business features require a paid plan
Browser extension Browser extension
Open source Closed source
License: AGPL-3.0 License not stated
Not stated if an account is needed Not stated if an account is needed
Not stated if it works offline Needs internet

Checked September 22, 2026

Checked September 24, 2026

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