- [Roundcube](https://roundcube.net) - Browser-based IMAP client with an application-like user interface. ([Source Code](https://github.com/roundcube/roundcubemail)) `GPL-3.0``PHP`
- [SnappyMail](https://snappymail.eu/) - Simple, modern, lightweight & fast web-based email client. (It is an actively developed fork of RainLoop). ([Demo](https://snappymail.eu/demo/), [Source Code](https://github.com/the-djmaze/snappymail)) `AGPL-3.0``PHP`
- [SquirrelMail](https://squirrelmail.org) - Another browser-based IMAP client. ([Source Code](https://sourceforge.net/p/squirrelmail/code/HEAD/tree/)) `GPL-2.0``PHP`