From what I can see, the only way to use the Adwords tool now is to start a paid campaign - are there any free alternatives that are worth using?
seobook.com . This is the best alternative. The link: http://tools.seobook.com/keyword-tools/seobook/
you can use keywordtool.io semrush ,.Keywords everywhere its very good as it will show you also estimated search volume etc
you may try moz.com/explorer/. Also, lsigraph is a nice tool for LSI (Latent Semantic Indexing) Keywords, or in other words - keywords, which are semantically related to your main keyword.
I tried different tools, but most of the time I just use keywordtool.io to get an idea of useful keywords in a specific niche.
I personally recommend Google Keyword planner only after that you can look for Semrush and wordstream. Google its self must have good keyword data of it's users. But other advertising platform might have additional data that could be useful to target your audience at lower rates and hit more conversions.
There are some free tools that work better that Keyword Planner from Adwords. I use 'Keywords Everywhere' that will show you keyword volume, cpc price, keyword suggestion..etc. It is a extension and I used with Google Chrome. Another tool is Kwfinder.com where you can see what keywords to use to rank ffast in Google.
the other alternatives look quite good, SEM Rush is no free tool, the trial version requires giving out your CC details, and the steep learning curve aint one for noobs I guess
I have been using keywordtool.io for keyword research for 2 years! I think it is the best alternative but it doesn't show the other metrics like avg monthly searches, prices unless you're a premium member!
one of the best keyword tool can also be google itself when you will search anything on google it will suggest some results and those are really great keywords and also most searchable. and also you can use Ubersuggest its free and by one of the most popular marketer Neil Patel. and also you can use buzzsumo to find popular articles and can use their title as their keyword are most searchable