10 Best Free Keyword Research Tools for Your Content Marketing [Update: April 2015]

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[Original article was published on 21.05.2014]

Keyword research can be a real pain in the ass for content marketers. Finding the right tool for making the process efficient and less time-consuming can be, too. That’s why we’d like to introduce some helpful and free keyword research tools for your daily workflow in content marketing to you.

The research process isn’t something you can just skip in case you don’t have time or resources available. On the contrary, finding the right keywords can determine the success or failure of a piece of content you may have already put a lot of sweat into. In the end, the right keywords are responsible for the visibility of your post, helping users to find your specific information as a perfect answer to their particular request.

This is also why, nowadays, we are rather looking for long-tail keywords corresponding to the question initiating a search query – such as “how to do keyword research” – instead of optimizing for single terms like “keyword”. Having said that, let’s move on to examining some of the keyword research options at hand.

[Editor’s Note]

Thanks for all your comments and suggestions on keyword research tools to be included in this article. Since you’ve pointed some really great alternatives suitable for extensive keyword research out to me, I decided to update this post and have a look at the options available now – about one year after my initial keyword research tool curation. However, this time I’ve defined specific evaluation criteria for ranking beforehand. My goal was to make my Top 10 more replicable and provide better insights into the origination process. In order to improve this list in the future, I’d like you to answer a few questions about your personal idea of the perfect keyword research tool before moving on to my carefully created list. Your input is very much appreciated, so many thanks in advance!

And please feel free to leave further suggestions on which tools to include in the comments. I will certainly consider your tips for my next article update. And now enjoy checking out what’s new in the keyword research market and have fun trying the various tools yourself!


How has Keyword Research changed?

When I first published this article, keyword research had already come a long way. What started off with specific search terms being relentlessly stuffed in a text and measured by pure keyword density had become an actual search query that users wanted to be answered by an article targeting and discussing the so-called long-tail keyword. Google Hummingbird had just started revolutionizing content marketing with its introduction of semantic search bringing context and synonyms more into focus. This change of algorithm clearly emphasized Google’s first and foremost goal: user focus. Technical aspects became less important while user experience began to take over.

Today, it is not enough to just research exact match keywords. It is also necessary to look at search intent, bounce rates, and dwelling time reflecting user behavior and thus user satisfaction. Proactively creating awareness for keyword-relevant content and building an authoritative brand upon this sustainable organic visibility is what SEOs should focus on in 2015. This also means working together closely with fellow disciplines such as inbound marketing and online PR to best leverage the beneficial synergy effects.

Keyword Research 2014 vs. 2015

10 Best Free Keyword Research Tools – Now vs. Then

My rundown of the 10 best free keyword research tools has changed along with the evolving concept of keyword strategy and the evolved method of evaluation of course. This time I tried and made my decision as transparent and comprehensible as possible. Following you’ll find the lists of my 10 best free keyword research tools now and then. In the new list I’ve marked tools that have climbed up in ranking, tools that have moved down in ranking as well as newcomers.

Here’s a quick overview of our rundown now vs. then:

10. Wordtracker


How it works

Wordtracker’s starting page is nice and clean and clearly focusses on starting your keyword research. After entering your keyword of choice you first of all get the 10 keyword with the highest search volume. If you choose to continue your research from here, Wordtracker displays competition for these same keywords and one step further calculates the so-called Key Efficiency Index (KEI) – a metric based on the relation between search volume and competition for a keyword. This metric intends to show you the highest possible keyword potential.



  • Displays a number of metrics such as search volume, competition, and KEI (relation traffic/competition).
  • Allows you to sort columns in ascending or descending order. (This function does not seem to work properly, however.)
  • Simple and intuitive starting page and research process.


  • Free version is limited to 10 search terms only, which is very little to start with.


9. Keyword Discovery


How it works

The free version of the tool is pretty basic, offering a list of keyword suggestions for a chosen term. Furthermore, last year’s search volume is displayed along with the results.

Keyword Discovery



  • Displays number of times that each keyword or phrase has been searched for over the last 12 months.
  • Keyword data is compiled and collected from various toolbar browsers and over 200 search engines worldwide.


  • Free version limited to hundred results only.


8. SEO Book


How it works

First of all, in order to make use of the keyword tool a free registration is necessary. In return, SEO Book offers suggestions on daily search volumes by market for Google and the Bing Yahoo! Search network for each keyword and also provides SEA metrics such as CPC and monthly value.

SEO Book



  • You can directly export the keyword list to CSV.
  • Relevant keyword metrics – e.g. daily search volume (broken down into search engines)/ price estimates for CPC and monthly value – are displayed free of cost.


  • Tool can’t be used at all without free registration.
  • Within the keyword research tool, only the whole keyword list or single terms can be exported, anything else requires the use of further tools (also offered by SEO Book for free).
  • The tool offers different search options such as “fuzzy match” and “G Trends” that aren’t further explained. The latter option used to integrate information from Google Trends beneath the keyword list. However, this information does not seem to be displayed anymore.


7. Wordstream


How it works

The tool grants 30 free searches to non-paying users. Just enter a word into the search bar and get further keyword ideas related to that very term. The results are then listed according to their relative frequency. The tool furthermore offers an option of sending all keywords directly to your e-mail account.




  • The first page of keyword results can be customized by removing items from the list.
  • You can filter all words containing a certain undesired keyword from your list.
  • The customized keyword list can be mailed and then downloaded in CSV format.
  • You can ‘nichefy’ your keywords for displaying corresponding groups in which the keyword fits.


  • The only metric provided is relative frequency as most metrics are blacked out in the free version.
  • You need to enter your e-mail address in order to get access to the complete list of keywords.


6. Übersuggest


How it works

It’s really pretty simple. You choose a keyword, a language, and a source, then click on “Suggest”. Subsequently, the tool extracts suggestions for the search term. For some keywords, there are further suggestions available which can be displayed with a click on the corresponding word. A plus sign gives you the possibility to add keywords to your list and then export them via copy and paste.




  • The tool can be used for free without any kind of registration needed.
  • All keywords found are clearly displayed in alphabetic order.
  • Results can be filtered for letters or numbers.
  • An individual keyword list can be created and exported via copy and paste.


  • The keywords are neither weighed nor prioritized in any way.


5. Keyword IO


How it works

Keyword IO allows you to enter a target phrase and choose a specific country to consider for your search. After hitting ‘analyze’, you then get to an overview of potential keyword phrases, keyword trends over time and Top 10 search engine results directly drawn from Google, as well as a listing of keywords based on TF•IDF and TextRank.

Keyword IO



  • Simple and intuitive starting page.
  • Keywords are listed clustered in long-tail and alphabetic order.
  • You can download the list of suggestions.
  • Shows relevant URLs for the specific keyword entered.
  • Shows and visualizes relevancy of terms based on TF•IDF and TextRank.


  • Only one query available without free signup.
  • Download only possible after free signup.
  • Some metrics require further explanation.


4. Keyword Suggestion Tool


How it works

You choose your search engine, country or language, put your keyword into the blank, and hit ‘search’. The tool then gives you suggestions for the most popular keywords that people usually search for. You can then drill down on each single item on the resulting keyword list by clicking on it and getting further long-tail keyword suggestions.

Keyword Suggestion Tool


  • Considers a huge number of search engines separately.
  • You can choose a language to search for.
  • You can further drill down on each single keyword on the list.


  • Does not display any metrics for further keyword analysis.
  • Curates keywords for a variety of search engines on one site, but does not feature auto complete.


3. Serpstat


How it works

Serpstat filters for your specific keyword and a chosen Google domain. You can then filter the resulting keyword list for ‘only questions’ or all keywords that start with a certain search term.




  • Looks at different Google domains separately.
  • Features auto complete.
  • You can choose to display “all”, “only questions”, or “start with XXX”.


  • No keyword metrics for a first evaluation.
  • Export only possible after free signup.


2. Keyword Eye


How it works

There is a free plan available, which includes 10 keyword searches per day, up to 100 keyword suggestions per report, and 25 Google country keyword databases. After registration, the keyword research can be further specified, if you’d like to receive keyword suggestions relating to a primary keyword, if you’d like to get search engine data for a number of specified keywords, or if you’d prefer to search via Autosuggest.

Keyword Eye



  • Research query can be customized.
  • The results are appealingly displayed in a customizable word cloud or in grid view depending on your preference.
  • You can visualize further search data.
  • You can directly compare a set of keywords regarding relevant metrics such as search volume and competition.
  • You can add selected keywords to a separate list for download.


  • You need to register in order to be able to use the tool.


1. Google


How it works

Google offers various free keyword research tools. The most popular and easiest way to get inspiration on long tail keywords probably is Google Suggest. This term describes the drop-down menu opening when simply typing single letters or words into the search bar. The order of offered terms is determined by using a wide range of information in order to decide which query users most likely want to see. The tool therefore provides important insights on potential keywords.

Google Suggest

Google Trends on the other hand visualizes the development of interest for certain search terms over time. It also displays regional interests and identifies related searches regarding general topics as well as specified queries. As the name implies, this is a handy tool for differentiating between trending topics, buzzwords and current issues at all times.

Google Trends & Keyword Tool

Last but not least Google Adwords, conceptualized for campaign planning, offers detailed insight into search volumes. This information is important when it comes to competitor analysis for particular search queries. In this regard, it would be a good idea to double check keywords derived from Google Suggest with the Keyword Planner in order to filter very in-demand search terms with the lowest possible competition.

Google Keyword Planner



  • In combination, these tools provide you with in-depth data on potential keywords.
  • All relevant metrics such as related searches, search volume and development of queries can be found.


  • You need to switch between the tabs.
  • There is no export option for Google Suggest search terms, for example.


Criteria and Free Keyword Research Tools Considered

Last but not least I want to let you know which evaluation criteria and free keyword research tools I’ve considered in order to come to this decision. First of all, I had to dismiss brainstorming, user surveys, and Wordpot from my original list of keyword tools. Brainstorming and user surveys were not comparable enough and Wordpot doesn’t seem to exist anymore. These changes gave other keyword tools – new and old – the opportunity to enter the Top 10 this time and mix up the results a little bit. Furthermore, this time, I followed pre-defined evaluation criteria to make my Top 10 more replicable. In the following, I will list the crucial rating criteria and the results of my analysis upon which the rundown above is based upon.
There were three main criteria that I’ve considered in the process.

  1. Functionality
  2. Keyword Output
  3. Usability & Design


1. Functionality

With functionality, the main focus lay on the following aspects:

  • tool shows a minimum of 100 keyword ideas without registration
  • tool displays relevant metrics (search volume, competition, PPC/CPC, trends) that are sorted or sortable
  • tool offers the possibility to create own projects or at least to modify the keyword list (add/delete)
  • tool allows to export results in any format

Keyword Research Tools Comparison

2. Keyword Output

This aspect made less of an impact compared to functionality or usability and design, because, in my opinion, it is not about creating the broadest list of keywords but rather about creating a high-quality list of keywords. I have thus taken keyword output into account but have given it lower priority in the overall evaluation.

  • Total amount of keywords delivered
  • Unique keywords delivered

Keyword Research Tool Comparison

3. Usability & Design

This was the most subjective matter to evaluate in my analysis. I decided to give each keyword research tool a grade from 1 (being the best possible grade) to 6 (being the worst possible grade). This part of the rating is highly prone to personal preferences, yet I’ll try and make it as transparent as possible by providing you my evaluation table.

Keyword Research Tool Comparison

What Makes the Best Keyword Research Tool:

There are many different versions of free keyword research tools but only few can:

  • display a considerable amount of keywords
  • weigh the results according to relevant metrics
  • offer intuitive usability and appealing design
  • AND export keywords individually to a certain project.

This is why Google ended up being my number one. Their free and easy-to-use keyword research tools manage to combine all of the factors listed above providing SEO and SEA metrics like search volume and PPC competition at once. However, you need to switch between the various functions Google offers. For those of you who would prefer to get a broad overview in one single and well-designed tool, the Keyword Eye might be a solution, since it managed to achieve the best results in functionality and usability. Last but not least, there is of course the option to invest in a keyword research tool like our Keyword Hunter combining everything you need and more… 😉
I’ll let you have the final say on this! Let me know in the comments which keyword research tools you are using and which ones you would recommend to others!

SEO Keyword Research Webinar

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Fenja Villeumier

Fenja Villeumier

Fenja Villeumier is inbound marketing manager at the linkbird company in Berlin. She is involved in content management at all stages from topic finding, conception and production to seeding. Her favorite leisure-time activities are reading, travelling, and photography.

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