Mailvelope is a free software for end-to-end encryption of email traffic inside of a web browser (Firefox or Chromium) that integrates itself into existing webmail applications. Developed by Thomas Oberndörfer
License: Open Source
Mailvelope focuses on providing strong encryption for webmail services, making it ideal for users needing robust security. Email.biz offers a more integrated approach with built-in features, making it user-friendly but less flexible regarding third-party services.