Apache Guacamole is a clientless remote desktop gateway allowing users to control remote computers or virtual machines via a web browser, and allows administrators to dictate how and whether users can connect using an extensible authentication and authorization system. Destination machines can be kept isolated behind Guacamole and need not be reachable over the internet. It is published under the Apache License 2.0, available for multiple platforms and maintained by the Apache Software Foundation.
Remote access is performed via the guacd component, which uses the RDP, VNC or SSH remote protocols to access resources. Guacamole is clientless and doesn't require an agent to be installed on the resources being accessed. The fact that the client runs on web browsers allows users to connect to their remote desktops without installing a remote desktop client.