Roundcube is a web-based IMAP email client. Roundcube's most prominent feature is the pervasive use of Ajax technology. Roundcube is free and open-source software subject to the terms of the GNU General Public License (GPL-3.0-or-later), with exceptions for skins and plugins. History After about two years of development the first stable release of Roundcube was announced in early 2008. Technology Roundcube is written in PHP and can be employed in conjunction with a LAMP stack, or any other operating systems that support PHP are supported as well. The web server needs access to the IMAP server hosting the email and to an SMTP server to be able to send messages. Roundcube Webmail is designed to run on standard web servers such as Apache, LiteSpeed, Nginx, Lighttpd, Hiawatha or Cherokee in conjunction with a relational database engine. Supported databases are MySQL, PostgreSQL and SQLite. The user interface is rendered in XHTML and CSS and is fully customizable with skins. Roundcube incorporates jQuery as part of its distribution, as well as other libraries such as GoogieSpell and TinyMCE. Plugins Starting with version 0.3, Roundcube introduced a plug-in API which allows non-standard features to be added without the need to modify the source code. A variety of plug-ins are available from the Plugin Repository. Project "Roundcube Next" On 3 May 2015, Roundcube announced, in partnership with Kolab Systems AG, that they planned to completely rewrite Roundcube and create Roundcube Next. A crowdfunding campaign was set up to finance the project. The goal of $80,000 was reached on June 24. The final amount raised was US$103,541. Roundcube Next was intended to include additional features like calendar, chat and file management. This was to be implemented using WebRTC and connectors from popular services like Dropbox and OwnCloud. However, Kolab Systems and Roundcube stopped development on the project in 2016, with no information or refunds provided to project backers, leading to a failed crowdfund. A Roundcube developer later claimed Roundcube had no ownership over the Roundcube Next campaign, despite its public engagement and ownership on the crowdfund page. Current features Ajax technology spread throughout the user interface, allowing features such as drag-and-drop message management Multilingual with over 70 languages Connects to any IMAPv4 server Encrypted TLSv1.2 connection to IMAP server using PHP5.6 SSL/TLS libraries Full support for MIME and HTML messages Sophisticated privacy protection Compose Richtext/HTML messages with attachments Multiple sender identities Threaded message listing IDNA