I've used SPDisposeCheck for SP2007/2010 and find it very useful for finding undisposed sp objects, but from this blog post, it's mentioned that it's no longer working for 2013.
Is there any alternatives available?
SPCop, the free tool of the SPCAF framework, will do the trick and even more. Have a look here: http://blogs.msdn.com/b/torstenmandelkow/archive/2013/10/08/free-sharepoint-code-analysis-tool-available.aspx
You can use the SPDisposechecker. In this tool, what you have to do is give the path of dll and the file where you want the output file. Example,
Perform SPDisposeChecker on dlls using command line
C:\Program Files\Microsoft\SharePoint Dispose Check>SPDisposeCheck C:\CODE\DisposeCheckDllfolder >Log100DII.xml
where 1) C:\Program Files\Microsoft\SharePoint Dispose Check --> path of dispose checker exe
2) SPDisposeCheck --> command(Keyword)
3) C:\CODE\DisposeCheckDllfolder --> where the dll of your solution is kept.
4) Log100DII.xml --> output file name will generate in the same folder of dll