NicheBOT.com would be worth it even if you had to pay for to access, at least at a reasonable fee. Like other tools, it lists alternative keyword suggestions, but it also breaks things down by major search engines and keyword phrases. The free version lists only the past 100 days, so you might want to use this service in conjunction with KeywordDiscovery.com to get long range statistics.
NicheBOT has been chosen as a top free resource because it offers a thesaurus, keyword ranking, and keyword tracking tools in addition to great keyword search features.
The tool has one drawback. You must enter a "captcha"—those image-based words and jumbled letters that test whether you're human or a robot—for each new search. You can avoid this, however, if you register, and registration is free.
KeywordDiscovery.com pulls information from 100 search engines. It offers web-wide statistics, related keyword searches, and a graph that shows seasonal trends. This resource is excellent for businesses that rely on seasonal income because you can see the month-by-month overall popularity of various keyword searches at a glance at any time during the year.
The WordTracker Keywords tool is a basic but solid free resource. It lists the number of searches made on keywords, as well as alternative or related keyword searches. You can view more than the top 100 related keywords if you join and sign up for a paid membership. WordTracker is simple to use but it doesn't lead to more comprehensive options. This user-friendly website is still solid for people who are just starting out in SEO.
Google gets a mention here because it remains the most prominent search engine online. Its keyword selector tool doesn't offer a lot of meaningful information, but if you plan to use online advertising—either sponsored links or pay-per-click services—it's worth taking a look at how Google ranks the competitiveness of your keyword phrases. The more competitive a keyword phrase, the more it costs to advertise using that phrase.
Although it's not necessarily a great tool for SEO, Google's AdWords can be useful in helping you decide which keywords to select, to determine a reasonable price or bid, and to decide which ad service to use.
The Top Free Keyword Selector and Comparison Tools
Your Business Depends on Keywords, so Get Them Right
Keywords are the lifeblood of your website. Visitors search for them online, and hopefully, they'll lead to your site—at least if you've done your research. You need to draw in traffic, and you need the right kind of traffic. Someone searching for the keyword "bass" won't stay at your fishing gear site long if he wants a new guitar.
So how do you find and select the perfect keywords? Several tools are available to help you along and many of them are free. Here are a few ranked according to how well they report results, how easy they are to use, and how useful the information returned is for search engine optimization—that coveted SEO.