Keyword Planner can do all of these things except:
suggest keywords and ad groups that may not have occurred to you
multiply keyword lists together
provide Quality Score estimates and validate keywords
provide historical statistics on search volume
Keyword Planner is a free AdWords tool for new or experienced advertisers that’s like a workshop for building new Search Network campaigns or expanding existing ones. You can search for keyword and ad group ideas, see how a list of keywords might perform, and even create a new keyword list by multiplying several lists of keywords together. Keyword Planner can also help you choose competitive bids and budgets to use with your campaigns.
Read more here: https://support.google.com/adwords/answer/2999770