KW Finder is similar to the Google Adwords tool; it even pulls up similar results, which aren’t as entirely on-point as the immediate results from SEMrush and Moz. From my experience with KW Finder, the searches are a lot better if you put some time into manually adding in filters like negative keywords and additional keywords you do want to include.
3. Ninja Outreach: Full disclosure this is my own tool, and it is actually an outreach tool, so you may be wondering how it plays into Keyword Research. The fact is there are quite a few data points that NinjaOutreach gets for me that I find useful in keyword research, such as the articles that are ranking for the keyword in Google, their domain authority, their page authority, the number of backlinks they have, and other social and contact data. It's pretty valuable stuff, especially if there is going to be an outreach campaign tied into the keyword research. I wrote a great article with Jake from LTP showing the combination of the two tools.
To get started with the Free Keyword Tool, just enter a keyword or search term into the relevant field. If you want to conduct competitive intelligence research into your competitors' keyword data, you can also enter the URL of a specific webpage to view keyword data for that page. You can also enter your industry and country to see even more accurate results; it's not unusual for the cost-per-click and other metrics to differ widely from one country to another, even for advertisers bidding on the same keywords in the same industry. 
3) Google: This is pretty straight forward but it’s the main reason I like it. I search for my main seed keyword in Google, and use the keywords that Google itself highlights in bold on the search results, plus the “Searches related to” section at the bottom to get keyword variations or LSI. That’s basically what Google is telling you that topic is about. No need for a thousands other tools. I use these to optimize the on page of my target pages as well.

As for the history of the company, as I explained, I created Long Tail Pro back in 2011.  At the time, I was creating tons of niche sites and was doing alot of keyword research and content creation.  I was trying to figure out what types of keywords would rank quickly in the search engines, specifically Google, and I was frustrated with the other keyword research tools (in particular Market Samurai) out there.