SolrTM Version Control
The Solr source code resides in the Apache Subversion (SVN) repository. The command-line SVN client can be obtained here or as an optional package for cygwin. The TortoiseSVN GUI client for Windows can be obtained here. There are also SVN plugins available for older versions of Eclipse and IntelliJ IDEA that don't have subversion support already included.
Web Access (read-only)
The source code can be browsed via the Web at http://svn.apache.org/viewcvs.cgi/lucene/dev/. No SVN client software is required.