Can anybody suggest me some good Long Tail Keyword tool?
Try our this one. <!-- m --><a class="postlink" href="http://keywordtool.io/">http://keywordtool.io/</a><!-- m -->
Its not exactly free but has a good free trial version.
Best online tools to find Long Tail Keywords are:
Answer the Public
SEMrush
KWfinder
Google Auto Suggests
Word Tracker Keyword Tools
UberSuggest
Long Tail Pro
Normally I use keywordtool.io, google suggest, and Google keywords planner, to me they are decent enough.
Most of the useful keyword tool today has a premium account but days of trial is really interesting.