Best free browser tester? (javascript issues with ipad, and andriod)

What is the best free browser tester? I have firefox and chrome. I am running into the issue where the page works fine on windows, but not in ipad, or certain versions of android. Its driving me nuts because it works fine in all chrome/firefox versions on windows and linux but not in ipad or certain versions of android. Any suggestions would greatly be appreciated.

the web page has javascript too.