apiGrove Core
You can download the source and create your own build, or download a build for Red Hat Enterprise Linux 5.8.
Graphical Front End
You must first install the apiGrove Core to use the graphical front end. It does not deliver all the capability of the command line, but it does provide access to the primary functionality.
apiGrove is an open source API manager built in Java on top of Fuse ESB. You can find out more about why and how it was built at apiGrove.net. The very short version is that it was built with these imperatives in mind:
apiGrove has been tested on Red Hat Enterprise Linux 5.8. More details.
Though it was started by Alcatel-Lucent, the apiGrove project is actively seeking users and contributors.