Roundcube is not available as a web app but there are plenty of alternatives that runs in the browser with similar functionality. The best Online alternative is Rainloop, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Roundcube and 17 are available as a web app so hopefully you can find a suitable replacement. Other interesting Online alternatives to Roundcube are Mailpile, Horde, Kolab and SOGo.
Simple, modern & fast web-based email client. Modest system requirements, decent performance, simple installation and upgrade, no database required. All these make RainLoop Webmail a perfect choice for your email solution.
Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features. The development of Mailpile is funded by a large community of backers and all code related to the project is and will be released under an OSI approved Free Software license.
Enterprise-level, browser-based suite for IMAP email, calendar, contacts, tasks, notes, wiki, and file management, offering syncing, shared and unlimited resources, multilingual support, customizable dashboard, and integration with mobile and external clients.
SOGo is groupware server with a focus on scalability and open standards.
SOGo provides a rich AJAX-based Web interface and supports multiple native clients through the use of standard protocols such as CalDAV, CardDAV and GroupDAV.Share your calendars, address books and mails in.
Zimbra Collaboration is an open, secure collaboration tool for email, calendaring, tasks and more. With the most innovative web application available today, Zimbra boosts the productivity of users on any desktop and dramatically reduces TCO compared to legacy platform vendors.
The OX App Suite by Open-Xchange is web-based platform offering a suite of apps like an email client, calendar, contacts magement, cloud storage with synchronization and productivity apps for word processing, spreadsheets and presentations.
Atmail webmail system offers a webmail client, email server platform and mailserver appliance for Linux, Unix and Windows.
Real-time email, chat, audio/video calls & conferences, file-sharing, and contacts app with a modern and intuitive UI.
Open Source WebMail Lite is a free community edition of full-featured WebMail Pro server application intended for users who need a clean and simple web mail application, which is fast and easy to use. Whether you need a free web browser based email client software for Windows ASP.
Microservice based webmail client built with ReactJS and Spring.
Minimalistic webmail client which currently has the main features of any other mail client (read mail, compose mail, organize mail folders...).
Estonia
EU
Switzerland
Canada
United States
Germany
Australia
Bosnia & Herzegovina
Spain
It's popular, modern programmed, faster than roundcube, but not so feature rich. Much sits below the surface though.