When you’re running the Rank Checker feature sometimes you see Google’s captchas pop up and which can be annoying. I have only experienced this on a computer with an old OS (Windows XP) though; I haven’t seen this on Windows 7 or Windows 10 machines. Again, if you close the software and reopen it after a few minutes, everything will be okay again. UPDATE: one of the latest updates fixed this issue.
What are people looking for on your site? These terms are keywords in the vocabulary of your actual audience and should definitely be added to your keyword list. Do not forget to look at the keywords people filled in that didn’t get any results: this was stuff people were expecting but didn’t find. You can look into the results of your internal search in Google Analytics at Behavior → Site Search → Search Terms.
Once you've entered a keyword, you'll be presented with a range of data: Google Search Volume, Competition, CPC, and Opportunity Score. This data provides advertisers with at-a-glance data that they can use as the basis for their next campaign. No other free keyword tool provides as much free keyword data as WordStream's new and improved Free Keyword Tool. Try it today and see how much easier keyword research can be with WordStream.
In Keyword Planner, formerly known as the Keyword Tool, you can get search volume and traffic estimates for keywords you're considering. Unfortunately, when Google transitioned from Keyword Tool to Keyword Planner, they stripped out a lot of the more interesting functionality. But you can make up for it a bit if you take the information you learn from Keyword Planner and use Google Trends to fill in some blanks.

You can use Keyword Researcher Pro with the best free keyword research tool out there, Google KW planner. Importing and exporting data is as easy as clicking a button. It’s all done at lightening speed too. There are tutorials of how to do this in video form on the sales page here and they show just how easy this tool is for finding those long tail keywords.

* Please note our tool currently assumes Google having ~ 83% of the market, with Bing + Yahoo! splitting the remaining 17% of the market. Actual market conditions may vary significantly from that due to a variety of factors including: search location, search market demographics, how much marketshare mobile search has relative to desktop in that particular vertical, etc.
The keywords you want to focus your SEO on should closely resemble the vocabulary of your audience. In order to come up with the proper keywords you really have to get inside the heads of the people who search for your website. What terms will people use? How do people search? Which question does your website answer? You should create a list of all search terms people could use and think of combinations and nuances within these search terms.

It would be great if you can provide comparative analysis of this tool with Google Keyword Planner. Since you’re using this tool so you can provide best comparison. One differentiation which I understood is that this tool works for yahoo and bing as well whereas Google keyword planner works only for Google but Google being a dominating search engine, gives the highest returns, so only this reason may not be enough to buy it.