I use the following Pay Per Click Testing Tools

A. A/B Split Test Calculator - makes it easy to test the probably of the accuracy of results from an A/B split test
B. AdComparator - multivariable advertisement analysis using the Taguchi Method

PPC Advertising is a dynamic marketplace, the higher you bid, the higher your advertisement will be displayed in the list. As the name suggests, you don't need to pay for listing, but only for real clicks hence is inorganic strategy. It allows you to get maximum exposure, while you control the amount you want to spend on your marketing campaign whereas SEO is organic and completely free of cost.

Hello Friends,

Tools to use

Keyword tool: https://adwords.google.com/select/KeywordToolExternal
First of all, conduct a thought shower of potential keywords which you think will help to generate traffic to your website and add them to the ‘Word or Phrase’ column of this keyword tool. Click ‘Search’ and wait for the tool to generate keywords related to your query.

Google Insights: http://www.google.com/insights/search/Google Insights is a strong PPC tool which can be used to compare search patterns across specific regions, time frames, categories and properties. With Google Insights, you can tweak AdWords campaigns by getting keyword ideas. Available in 39 languages, this PPC tool provides you with the facility to download data into spreadsheets. Google Insights also provides a graphical representation of data based on search which goes back until 2004. This tool is also available to users free of charge.

Google Wonder Wheel: http://www.googlewonderwheel.com/
This is another free PPC tool which allows you to see systematic results to a search query, allowing you to explore more relevant search terms that might be related to the ones you are already searching for.

Thanks