MailStore - MailStore Home - A 100% free single-private-user desktop solution
Roundcube - Web-based IMAP email client
Gmvault - Backup the emails in your Gmail account.
Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.
SysTools Gmail Backup - Backup Gmail Emails, Contacts, Calendar, and Google Drive Storage File by SysTools Gmail Backup Solution
Mailpile - Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.