<p>I've only been able to find two thus far, namely <a href="http://tinyradius.sourceforge.net/" rel="nofollow noreferrer">TinyRadius</a>, which itself discourages production use and <a href="http://www.axlradius.com/" rel="nofollow noreferrer">AXL</a>, which is pay-only.</p>

<p><a href="http://coova.org/wiki/index.php/JRadius" rel="nofollow noreferrer">JRadius</a> seems tied to <a href="http://freeradius.org/" rel="nofollow noreferrer">FreeRADIUS</a>, which isn't a library and will need a lot of cajoling to function like one.</p>

[{'answer_id': 80536, 'author': 'Epaga', 'author_id': 6583, 'author_profile': 'https://Stackoverflow.com/users/6583', 'pm_score': 2, 'selected': False, 'text': '<p>List from <a href="http://freeradius.org/related/opensource.html" rel="nofollow noreferrer">http://freeradius.org/related/opensource.html</a> (not copying the descriptions because the page says it\'s copyright <em>rolleyes</em>):</p>\n\n<p>Cistron - <a href="http://www.radius.cistron.nl/" rel="nofollow noreferrer">http://www.radius.cistron.nl/</a></p>\n\n<p>GNU Radius - <a href="http://www.gnu.org/software/radius/" rel="nofollow noreferrer">http://www.gnu.org/software/radius/</a></p>\n\n<p>FreeRADIUS - <a href="http://freeradius.org/" rel="nofollow noreferrer">http://freeradius.org/</a></p>\n\n<p>JRadius - <a href="http://www.coova.org/JRadius" rel="nofollow noreferrer">http://www.coova.org/JRadius</a></p>\n\n<p>ICRADIUS - <a href="http://www.icradius.org/" rel="nofollow noreferrer">http://www.icradius.org/</a></p>\n\n<p>OpenRADIUS - <a href="http://www.openradius.net/" rel="nofollow noreferrer">http://www.openradius.net/</a></p>\n\n<p>XtRADIUS - <a href="http://xtradius.sourceforge.net/" rel="nofollow noreferrer">http://xtradius.sourceforge.net/</a></p>\n\n<p>YARD RADIUS - <a href="http://sourceforge.net/projects/yardradius" rel="nofollow noreferrer">http://sourceforge.net/projects/yardradius</a></p>\n'}, {'answer_id': 161617, 'author': 'Marius Marais', 'author_id': 13455, 'author_profile': 'https://Stackoverflow.com/users/13455', 'pm_score': 2, 'selected': False, 'text': "<p>OK, it seems a pure JAVA open-source RADIUS server simply does not exist.  </p>\n\n<p>For completeness, I think I'm going to try one of the Python implementations through Jython to get it running in Java and start replacing pieces as and when needed.</p>\n"}, {'answer_id': 32963933, 'author': 'Pierre Smits', 'author_id': 4365894, 'author_profile': 'https://Stackoverflow.com/users/4365894', 'pm_score': 1, 'selected': False, 'text': '<p>The Apache Directory project (<a href="http://directory.apache.org" rel="nofollow">http://directory.apache.org</a>) is looking into this as people are intending to donate some java code. If and when this is successfully concluded, we (the Directory community) will most probably start a sub project and build a community to further this code into a full-fledged java based Open Source Radius server.</p>\n'}]
['https://Stackoverflow.com/questions/76217', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/13455/']